class Sequel::Dataset

A dataset represents an SQL query. Datasets can be used to select, insert, update and delete records.

Query results are always retrieved on demand, so a dataset can be kept around and reused indefinitely (datasets never cache results):

my_posts = DB[:posts].where(author: 'david') # no records are retrieved
my_posts.all # records are retrieved
my_posts.all # records are retrieved again

Datasets are frozen and use a functional style where modification methods return modified copies of the the dataset. This allows you to reuse datasets:

posts = DB[:posts]
davids_posts = posts.where(author: 'david')
old_posts = posts.where{stamp < Date.today - 7}
davids_old_posts = davids_posts.where{stamp < Date.today - 7}

Datasets are Enumerable objects, so they can be manipulated using many of the Enumerable methods, such as map and inject. Note that there are some methods that Dataset defines that override methods defined in Enumerable and result in different behavior, such as select and group_by.

For more information, see the “Dataset Basics” guide.

Constants

OPTS
TRUE_FREEZE

Whether Dataset#freeze can actually freeze datasets. True only on ruby 2.4+, as it requires clone(freeze: false)

1 - Methods that return modified datasets

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Constants

COLUMN_CHANGE_OPTS

The dataset options that require the removal of cached columns if changed.

CONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. inner_join) that call join_table with the symbol, passing along the arguments and block from the method call.

EMPTY_ARRAY
EXTENSIONS

Hash of extension name symbols to callable objects to load the extension into the Dataset object (usually by extending it with a module defined in the extension).

EXTENSION_MODULES

Hash of extension name symbols to modules to load to implement the extension.

JOIN_METHODS

All methods that return modified datasets with a joined table added.

NON_SQL_OPTIONS

Which options don't affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.

QUERY_METHODS

Methods that return modified datasets

SIMPLE_SELECT_ALL_ALLOWED_FROM

From types allowed to be considered a simple_select_all

UNCONDITIONED_JOIN_TYPES

These symbols have _join methods created (e.g. natural_join). They accept a table argument and options hash which is passed to join_table, and they raise an error if called with a block.

Public Class Methods

register_extension(ext, mod=nil, &block) click to toggle source

Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should be a Module that will be included in the dataset's class. This also registers a Database extension that will extend all of the database's datasets.

   # File lib/sequel/dataset/query.rb
55 def self.register_extension(ext, mod=nil, &block)
56   if mod
57     raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block
58     if mod.is_a?(Module)
59       block = proc{|ds| ds.extend(mod)}
60       Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)}
61       Sequel.synchronize{EXTENSION_MODULES[ext] = mod}
62     else
63       block = mod
64     end
65   end
66 
67   unless mod.is_a?(Module)
68     Sequel::Deprecation.deprecate("Providing a block or non-module to Sequel::Dataset.register_extension is deprecated and support for it will be removed in Sequel 6.")
69   end
70 
71   Sequel.synchronize{EXTENSIONS[ext] = block}
72 end

Public Instance Methods

_clone(opts = nil || (return self))

Save original clone implementation, as some other methods need to call it internally.

Alias for: clone
clone(opts = nil || (return self)) click to toggle source

Returns a new clone of the dataset with the given options merged. If the options changed include options in COLUMN_CHANGE_OPTS, the cached columns are deleted. This method should generally not be called directly by user code.

Calls superclass method
   # File lib/sequel/dataset/query.rb
90 def clone(opts = nil || (return self))
91   # return self used above because clone is called by almost all
92   # other query methods, and it is the fastest approach
93   c = super(:freeze=>false)
94   c.opts.merge!(opts)
95   unless opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
96     c.clear_columns_cache
97   end
98   c.freeze
99 end
Also aliased as: _clone
distinct(*args, &block) click to toggle source

Returns a copy of the dataset with the SQL DISTINCT clause. The DISTINCT clause is used to remove duplicate rows from the output. If arguments are provided, uses a DISTINCT ON clause, in which case it will only be distinct on those columns, instead of all returned columns. If a block is given, it is treated as a virtual row block, similar to where. Raises an error if arguments are given and DISTINCT ON is not supported.

DB[:items].distinct # SQL: SELECT DISTINCT * FROM items
DB[:items].order(:id).distinct(:id) # SQL: SELECT DISTINCT ON (id) * FROM items ORDER BY id
DB[:items].order(:id).distinct{func(:id)} # SQL: SELECT DISTINCT ON (func(id)) * FROM items ORDER BY id

There is support for emulating the DISTINCT ON support in MySQL, but it does not support the ORDER of the dataset, and also doesn't work in many cases if the ONLY_FULL_GROUP_BY sql_mode is used, which is the default on MySQL 5.7.5+.

    # File lib/sequel/dataset/query.rb
129 def distinct(*args, &block)
130   virtual_row_columns(args, block)
131   if args.empty?
132     return self if opts[:distinct] == EMPTY_ARRAY
133     cached_dataset(:_distinct_ds){clone(:distinct => EMPTY_ARRAY)}
134   else
135     raise(InvalidOperation, "DISTINCT ON not supported") unless supports_distinct_on?
136     clone(:distinct => args.freeze)
137   end
138 end
except(dataset, opts=OPTS) click to toggle source

Adds an EXCEPT clause using a second dataset object. An EXCEPT compound dataset returns all rows in the current dataset that are not in the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use EXCEPT ALL instead of EXCEPT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].except(DB[:other_items])
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS t1

DB[:items].except(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items EXCEPT ALL SELECT * FROM other_items

DB[:items].except(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items EXCEPT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
157 def except(dataset, opts=OPTS)
158   raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
159   raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
160   compound_clone(:except, dataset, opts)
161 end
exclude(*cond, &block) click to toggle source

Performs the inverse of Dataset#where. Note that if you have multiple filter conditions, this is not the same as a negation of all conditions.

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

DB[:items].exclude(category: 'software', id: 3)
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

Also note that SQL uses 3-valued boolean logic (true, false, NULL), so the inverse of a true condition is a false condition, and will still not match rows that were NULL originally. If you take the earlier example:

DB[:items].exclude(category: 'software')
# SELECT * FROM items WHERE (category != 'software')

Note that this does not match rows where category is NULL. This is because NULL is an unknown value, and you do not know whether or not the NULL category is software. You can explicitly specify how to handle NULL values if you want:

DB[:items].exclude(Sequel.~(category: nil) & {category: 'software'})
# SELECT * FROM items WHERE ((category IS NULL) OR (category != 'software'))
    # File lib/sequel/dataset/query.rb
187 def exclude(*cond, &block)
188   add_filter(:where, cond, true, &block)
189 end
exclude_having(*cond, &block) click to toggle source

Inverts the given conditions and adds them to the HAVING clause.

DB[:items].select_group(:name).exclude_having{count(name) < 2}
# SELECT name FROM items GROUP BY name HAVING (count(name) >= 2)

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
198 def exclude_having(*cond, &block)
199   add_filter(:having, cond, true, &block)
200 end
extension(*exts) click to toggle source

Return a clone of the dataset loaded with the given dataset extensions. If no related extension file exists or the extension does not have specific support for Dataset objects, an error will be raised.

    # File lib/sequel/dataset/query.rb
206 def extension(*exts)
207   exts.each{|ext| Sequel.extension(ext) unless Sequel.synchronize{EXTENSIONS[ext]}}
208   mods = exts.map{|ext| Sequel.synchronize{EXTENSION_MODULES[ext]}}
209   if mods.all?
210     with_extend(*mods)
211   else
212     with_extend(DeprecatedSingletonClassMethods).extension(*exts)
213   end
214 end
filter(*cond, &block) click to toggle source

Alias for where.

    # File lib/sequel/dataset/query.rb
226 def filter(*cond, &block)
227   where(*cond, &block)
228 end
for_update() click to toggle source

Returns a cloned dataset with a :update lock style.

DB[:table].for_update # SELECT * FROM table FOR UPDATE
    # File lib/sequel/dataset/query.rb
233 def for_update
234    return self if opts[:lock] == :update
235   cached_dataset(:_for_update_ds){lock_style(:update)}
236 end
from(*source, &block) click to toggle source

Returns a copy of the dataset with the source changed. If no source is given, removes all tables. If multiple sources are given, it is the same as using a CROSS JOIN (cartesian product) between all tables. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].from # SQL: SELECT *
DB[:items].from(:blah) # SQL: SELECT * FROM blah
DB[:items].from(:blah, :foo) # SQL: SELECT * FROM blah, foo
DB[:items].from{fun(arg)} # SQL: SELECT * FROM fun(arg)
    # File lib/sequel/dataset/query.rb
247 def from(*source, &block)
248   virtual_row_columns(source, block)
249   table_alias_num = 0
250   ctes = nil
251   source.map! do |s|
252     case s
253     when Dataset
254       if hoist_cte?(s)
255         ctes ||= []
256         ctes += s.opts[:with]
257         s = s.clone(:with=>nil)
258       end
259       SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
260     when Symbol
261       sch, table, aliaz = split_symbol(s)
262       if aliaz
263         s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
264         SQL::AliasedExpression.new(s, aliaz.to_sym)
265       else
266         s
267       end
268     else
269       s
270     end
271   end
272   o = {:from=>source.empty? ? nil : source.freeze}
273   o[:with] = ((opts[:with] || EMPTY_ARRAY) + ctes).freeze if ctes
274   o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
275   clone(o)
276 end
from_self(opts=OPTS) click to toggle source

Returns a dataset selecting from the current dataset. Options:

:alias

Controls the alias of the table

:column_aliases

Also aliases columns, using derived column lists. Only used in conjunction with :alias.

ds = DB[:items].order(:name).select(:id, :name)
# SELECT id,name FROM items ORDER BY name

ds.from_self
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS t1

ds.from_self(alias: :foo)
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo

ds.from_self(alias: :foo, column_aliases: [:c1, :c2])
# SELECT * FROM (SELECT id, name FROM items ORDER BY name) AS foo(c1, c2)
    # File lib/sequel/dataset/query.rb
295 def from_self(opts=OPTS)
296   fs = {}
297   @opts.keys.each{|k| fs[k] = nil unless non_sql_option?(k)}
298   pr = proc do
299     c = clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self)
300     if cols = _columns
301       c.send(:columns=, cols)
302     end
303     c
304   end
305 
306   opts.empty? ? cached_dataset(:_from_self_ds, &pr) : pr.call
307 end
grep(columns, patterns, opts=OPTS) click to toggle source

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions if the database supports that. Note that the total number of pattern matches will be Array(columns).length * Array(terms).length, which could cause performance issues.

Options (all are boolean):

:all_columns

All columns must be matched to any of the given patterns.

:all_patterns

All patterns must match at least one of the columns.

:case_insensitive

Use a case insensitive pattern match (the default is case sensitive if the database supports it).

If both :all_columns and :all_patterns are true, all columns must match all patterns.

Examples:

dataset.grep(:a, '%test%')
# SELECT * FROM items WHERE (a LIKE '%test%' ESCAPE '\')

dataset.grep([:a, :b], %w'%test% foo')
# SELECT * FROM items WHERE ((a LIKE '%test%' ESCAPE '\') OR (a LIKE 'foo' ESCAPE '\')
#   OR (b LIKE '%test%' ESCAPE '\') OR (b LIKE 'foo' ESCAPE '\'))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (b LIKE '%foo%' ESCAPE '\'))
#   AND ((a LIKE '%bar%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_columns: true)
# SELECT * FROM a WHERE (((a LIKE '%foo%' ESCAPE '\') OR (a LIKE '%bar%' ESCAPE '\'))
#   AND ((b LIKE '%foo%' ESCAPE '\') OR (b LIKE '%bar%' ESCAPE '\')))

dataset.grep([:a, :b], %w'%foo% %bar%', all_patterns: true, all_columns: true)
# SELECT * FROM a WHERE ((a LIKE '%foo%' ESCAPE '\') AND (b LIKE '%foo%' ESCAPE '\')
#   AND (a LIKE '%bar%' ESCAPE '\') AND (b LIKE '%bar%' ESCAPE '\'))
    # File lib/sequel/dataset/query.rb
344 def grep(columns, patterns, opts=OPTS)
345   column_op = opts[:all_columns] ? :AND : :OR
346   if opts[:all_patterns]
347     conds = Array(patterns).map do |pat|
348       SQL::BooleanExpression.new(column_op, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
349     end
350     where(SQL::BooleanExpression.new(:AND, *conds))
351   else
352     conds = Array(columns).map do |c|
353       SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
354     end
355     where(SQL::BooleanExpression.new(column_op, *conds))
356   end
357 end
group(*columns, &block) click to toggle source

Returns a copy of the dataset with the results grouped by the value of the given columns. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].group(:id) # SELECT * FROM items GROUP BY id
DB[:items].group(:id, :name) # SELECT * FROM items GROUP BY id, name
DB[:items].group{[a, sum(b)]} # SELECT * FROM items GROUP BY a, sum(b)
    # File lib/sequel/dataset/query.rb
366 def group(*columns, &block)
367   virtual_row_columns(columns, block)
368   clone(:group => (columns.compact.empty? ? nil : columns.freeze))
369 end
group_and_count(*columns, &block) click to toggle source

Returns a dataset grouped by the given column with count by group. Column aliases may be supplied, and will be included in the select clause. If a block is given, it is treated as a virtual row block, similar to where.

Examples:

DB[:items].group_and_count(:name).all
# SELECT name, count(*) AS count FROM items GROUP BY name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count(:first_name, :last_name).all
# SELECT first_name, last_name, count(*) AS count FROM items GROUP BY first_name, last_name
# => [{:first_name=>'a', :last_name=>'b', :count=>1}, ...]

DB[:items].group_and_count(Sequel[:first_name].as(:name)).all
# SELECT first_name AS name, count(*) AS count FROM items GROUP BY first_name
# => [{:name=>'a', :count=>1}, ...]

DB[:items].group_and_count{substr(:first_name, 1, 1).as(:initial)}.all
# SELECT substr(first_name, 1, 1) AS initial, count(*) AS count FROM items GROUP BY substr(first_name, 1, 1)
# => [{:initial=>'a', :count=>1}, ...]
    # File lib/sequel/dataset/query.rb
397 def group_and_count(*columns, &block)
398   select_group(*columns, &block).select_append(COUNT_OF_ALL_AS_COUNT)
399 end
group_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the list of existing columns to group on. If no existing columns are present this method simply sets the columns as the initial ones to group on.

DB[:items].group_append(:b) # SELECT * FROM items GROUP BY b
DB[:items].group(:a).group_append(:b) # SELECT * FROM items GROUP BY a, b
    # File lib/sequel/dataset/query.rb
407 def group_append(*columns, &block)
408   columns = @opts[:group] + columns if @opts[:group]
409   group(*columns, &block)
410 end
group_by(*columns, &block) click to toggle source

Alias of group

    # File lib/sequel/dataset/query.rb
372 def group_by(*columns, &block)
373   group(*columns, &block)
374 end
group_cube() click to toggle source

Adds the appropriate CUBE syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
413 def group_cube
414   raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
415   clone(:group_options=>:cube)
416 end
group_rollup() click to toggle source

Adds the appropriate ROLLUP syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
419 def group_rollup
420   raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
421   clone(:group_options=>:rollup)
422 end
grouping_sets() click to toggle source

Adds the appropriate GROUPING SETS syntax to GROUP BY.

    # File lib/sequel/dataset/query.rb
425 def grouping_sets
426   raise Error, "GROUP BY GROUPING SETS not supported on #{db.database_type}" unless supports_grouping_sets?
427   clone(:group_options=>:"grouping sets")
428 end
having(*cond, &block) click to toggle source

Returns a copy of the dataset with the HAVING conditions changed. See where for argument types.

DB[:items].group(:sum).having(sum: 10)
# SELECT * FROM items GROUP BY sum HAVING (sum = 10)
    # File lib/sequel/dataset/query.rb
434 def having(*cond, &block)
435   add_filter(:having, cond, &block)
436 end
intersect(dataset, opts=OPTS) click to toggle source

Adds an INTERSECT clause using a second dataset object. An INTERSECT compound dataset returns all rows in both the current dataset and the given dataset. Raises an InvalidOperation if the operation is not supported. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use INTERSECT ALL instead of INTERSECT, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].intersect(DB[:other_items])
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS t1

DB[:items].intersect(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items INTERSECT ALL SELECT * FROM other_items

DB[:items].intersect(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items INTERSECT SELECT * FROM other_items) AS i
    # File lib/sequel/dataset/query.rb
455 def intersect(dataset, opts=OPTS)
456   raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
457   raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
458   compound_clone(:intersect, dataset, opts)
459 end
invert() click to toggle source

Inverts the current WHERE and HAVING clauses. If there is neither a WHERE or HAVING clause, adds a WHERE clause that is always false.

DB[:items].where(category: 'software').invert
# SELECT * FROM items WHERE (category != 'software')

DB[:items].where(category: 'software', id: 3).invert
# SELECT * FROM items WHERE ((category != 'software') OR (id != 3))

See documentation for exclude for how inversion is handled in regards to SQL 3-valued boolean logic.

    # File lib/sequel/dataset/query.rb
472 def invert
473   cached_dataset(:_invert_ds) do
474     having, where = @opts.values_at(:having, :where)
475     if having.nil? && where.nil?
476       where(false)
477     else
478       o = {}
479       o[:having] = SQL::BooleanExpression.invert(having) if having
480       o[:where] = SQL::BooleanExpression.invert(where) if where
481       clone(o)
482     end
483   end
484 end
join(*args, &block) click to toggle source

Alias of inner_join

    # File lib/sequel/dataset/query.rb
487 def join(*args, &block)
488   inner_join(*args, &block)
489 end
join_table(type, table, expr=nil, options=OPTS) { |table_name, last_alias, opts || EMPTY_ARRAY| ... } click to toggle source

Returns a joined dataset. Not usually called directly, users should use the appropriate join method (e.g. join, left_join, natural_join, cross_join) which fills in the type argument.

Takes the following arguments:

type

The type of join to do (e.g. :inner)

table

table to join into the current dataset. Generally one of the following types:

String, Symbol

identifier used as table or view name

Dataset

a subselect is performed with an alias of tN for some value of N

SQL::Function

set returning function

SQL::AliasedExpression

already aliased expression. Uses given alias unless overridden by the :table_alias option.

expr

conditions used when joining, depends on type:

Hash, Array of pairs

Assumes key (1st arg) is column of joined table (unless already qualified), and value (2nd arg) is column of the last joined or primary table (or the :implicit_qualifier option). To specify multiple conditions on a single joined table column, you must use an array. Uses a JOIN with an ON clause.

Array

If all members of the array are symbols, considers them as columns and uses a JOIN with a USING clause. Most databases will remove duplicate columns from the result set if this is used.

nil

If a block is not given, doesn't use ON or USING, so the JOIN should be a NATURAL or CROSS join. If a block is given, uses an ON clause based on the block, see below.

otherwise

Treats the argument as a filter expression, so strings are considered literal, symbols specify boolean columns, and Sequel expressions can be used. Uses a JOIN with an ON clause.

options

a hash of options, with the following keys supported:

:table_alias

Override the table alias used when joining. In general you shouldn't use this option, you should provide the appropriate SQL::AliasedExpression as the table argument.

:implicit_qualifier

The name to use for qualifying implicit conditions. By default, the last joined or primary table is used.

:join_using

Force the using of JOIN USING, even if expr is not an array of symbols.

:reset_implicit_qualifier

Can set to false to ignore this join when future joins determine qualifier for implicit conditions.

:qualify

Can be set to false to not do any implicit qualification. Can be set to :deep to use the Qualifier AST Transformer, which will attempt to qualify subexpressions of the expression tree. Can be set to :symbol to only qualify symbols. Defaults to the value of default_join_table_qualification.

block

The block argument should only be given if a JOIN with an ON clause is used, in which case it yields the table alias/name for the table currently being joined, the table alias/name for the last joined (or first table), and an array of previous SQL::JoinClause. Unlike where, this block is not treated as a virtual row block.

Examples:

DB[:a].join_table(:cross, :b)
# SELECT * FROM a CROSS JOIN b

DB[:a].join_table(:inner, DB[:b], c: d)
# SELECT * FROM a INNER JOIN (SELECT * FROM b) AS t1 ON (t1.c = a.d)

DB[:a].join_table(:left, Sequel[:b].as(:c), [:d])
# SELECT * FROM a LEFT JOIN b AS c USING (d)

DB[:a].natural_join(:b).join_table(:inner, :c) do |ta, jta, js|
  (Sequel.qualify(ta, :d) > Sequel.qualify(jta, :e)) & {Sequel.qualify(ta, :f)=>DB.from(js.first.table).select(:g)}
end
# SELECT * FROM a NATURAL JOIN b INNER JOIN c
#   ON ((c.d > b.e) AND (c.f IN (SELECT g FROM b)))
    # File lib/sequel/dataset/query.rb
551 def join_table(type, table, expr=nil, options=OPTS, &block)
552   if hoist_cte?(table)
553     s, ds = hoist_cte(table)
554     return s.join_table(type, ds, expr, options, &block)
555   end
556 
557   using_join = options[:join_using] || (expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)})
558   if using_join && !supports_join_using?
559     h = {}
560     expr.each{|e| h[e] = e}
561     return join_table(type, table, h, options)
562   end
563 
564   table_alias = options[:table_alias]
565 
566   if table.is_a?(SQL::AliasedExpression)
567     table_expr = if table_alias
568       SQL::AliasedExpression.new(table.expression, table_alias, table.columns)
569     else
570       table
571     end
572     table = table_expr.expression
573     table_name = table_alias = table_expr.alias
574   elsif table.is_a?(Dataset)
575     if table_alias.nil?
576       table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
577       table_alias = dataset_alias(table_alias_num)
578     end
579     table_name = table_alias
580     table_expr = SQL::AliasedExpression.new(table, table_alias)
581   else
582     table, implicit_table_alias = split_alias(table)
583     table_alias ||= implicit_table_alias
584     table_name = table_alias || table
585     table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table
586   end
587 
588   join = if expr.nil? and !block
589     SQL::JoinClause.new(type, table_expr)
590   elsif using_join
591     raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
592     SQL::JoinUsingClause.new(expr, type, table_expr)
593   else
594     last_alias = options[:implicit_qualifier] || @opts[:last_joined_table] || first_source_alias
595     qualify_type = options[:qualify]
596     if Sequel.condition_specifier?(expr)
597       expr = expr.map do |k, v|
598         qualify_type = default_join_table_qualification if qualify_type.nil?
599         case qualify_type
600         when false
601           nil # Do no qualification
602         when :deep
603           k = Sequel::Qualifier.new(table_name).transform(k)
604           v = Sequel::Qualifier.new(last_alias).transform(v)
605         else
606           k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
607           v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
608         end
609         [k,v]
610       end
611       expr = SQL::BooleanExpression.from_value_pairs(expr)
612     end
613     if block
614       expr2 = yield(table_name, last_alias, @opts[:join] || EMPTY_ARRAY)
615       expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
616     end
617     SQL::JoinOnClause.new(expr, type, table_expr)
618   end
619 
620   opts = {:join => ((@opts[:join] || EMPTY_ARRAY) + [join]).freeze}
621   opts[:last_joined_table] = table_name unless options[:reset_implicit_qualifier] == false
622   opts[:num_dataset_sources] = table_alias_num if table_alias_num
623   clone(opts)
624 end
lateral() click to toggle source

Marks this dataset as a lateral dataset. If used in another dataset's FROM or JOIN clauses, it will surround the subquery with LATERAL to enable it to deal with previous tables in the query:

DB.from(:a, DB[:b].where(Sequel[:a][:c]=>Sequel[:b][:d]).lateral)
# SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))
    # File lib/sequel/dataset/query.rb
645 def lateral
646   return self if opts[:lateral]
647   cached_dataset(:_lateral_ds){clone(:lateral=>true)}
648 end
limit(l, o = (no_offset = true; nil)) click to toggle source

If given an integer, the dataset will contain only the first l results. If given a range, it will contain only those at offsets within that range. If a second argument is given, it is used as an offset. To use an offset without a limit, pass nil as the first argument.

DB[:items].limit(10) # SELECT * FROM items LIMIT 10
DB[:items].limit(10, 20) # SELECT * FROM items LIMIT 10 OFFSET 20
DB[:items].limit(10...20) # SELECT * FROM items LIMIT 10 OFFSET 10
DB[:items].limit(10..20) # SELECT * FROM items LIMIT 11 OFFSET 10
DB[:items].limit(nil, 20) # SELECT * FROM items OFFSET 20
    # File lib/sequel/dataset/query.rb
660 def limit(l, o = (no_offset = true; nil))
661   return from_self.limit(l, o) if @opts[:sql]
662 
663   if l.is_a?(Range)
664     no_offset = false
665     o = l.first
666     l = l.last - l.first + (l.exclude_end? ? 0 : 1)
667   end
668   l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
669   if l.is_a?(Integer)
670     raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
671   end
672 
673   ds = clone(:limit=>l)
674   ds = ds.offset(o) unless no_offset
675   ds
676 end
lock_style(style) click to toggle source

Returns a cloned dataset with the given lock style. If style is a string, it will be used directly. You should never pass a string to this method that is derived from user input, as that can lead to SQL injection.

A symbol may be used for database independent locking behavior, but all supported symbols have separate methods (e.g. for_update).

DB[:items].lock_style('FOR SHARE NOWAIT')
# SELECT * FROM items FOR SHARE NOWAIT
DB[:items].lock_style('FOR UPDATE OF table1 SKIP LOCKED')
# SELECT * FROM items FOR UPDATE OF table1 SKIP LOCKED
    # File lib/sequel/dataset/query.rb
690 def lock_style(style)
691   clone(:lock => style)
692 end
merge_delete(&block) click to toggle source

Return a dataset with a WHEN MATCHED THEN DELETE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_delete
# WHEN MATCHED THEN DELETE

merge_delete{a > 30}
# WHEN MATCHED AND (a > 30) THEN DELETE
    # File lib/sequel/dataset/query.rb
703 def merge_delete(&block)
704   _merge_when(:type=>:delete, &block)
705 end
merge_insert(*values, &block) click to toggle source

Return a dataset with a WHEN NOT MATCHED THEN INSERT clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

The arguments provided can be any arguments that would be accepted by insert.

merge_insert(i1: :i2, a: Sequel[:b]+11)
# WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))

merge_insert(:i2, Sequel[:b]+11){a > 30}
# WHEN NOT MATCHED AND (a > 30) THEN INSERT VALUES (i2, (b + 11))
    # File lib/sequel/dataset/query.rb
719 def merge_insert(*values, &block)
720   _merge_when(:type=>:insert, :values=>values, &block)
721 end
merge_update(values, &block) click to toggle source

Return a dataset with a WHEN MATCHED THEN UPDATE clause added to the MERGE statement. If a block is passed, treat it as a virtual row and use it as additional conditions for the match.

merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20)
# WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

merge_update(i1: :i2){a > 30}
# WHEN MATCHED AND (a > 30) THEN UPDATE SET i1 = i2
    # File lib/sequel/dataset/query.rb
732 def merge_update(values, &block)
733   _merge_when(:type=>:update, :values=>values, &block)
734 end
merge_using(source, join_condition) click to toggle source

Return a dataset with the source and join condition to use for the MERGE statement.

merge_using(:m2, i1: :i2)
# USING m2 ON (i1 = i2)
    # File lib/sequel/dataset/query.rb
740 def merge_using(source, join_condition)
741   clone(:merge_using => [source, join_condition].freeze)
742 end
naked() click to toggle source

Returns a cloned dataset without a row_proc.

ds = DB[:items].with_row_proc(:invert.to_proc)
ds.all # => [{2=>:id}]
ds.naked.all # => [{:id=>2}]
    # File lib/sequel/dataset/query.rb
749 def naked
750   return self unless opts[:row_proc]
751   cached_dataset(:_naked_ds){with_row_proc(nil)}
752 end
nowait() click to toggle source

Returns a copy of the dataset that will raise a DatabaseLockTimeout instead of waiting for rows that are locked by another transaction

DB[:items].for_update.nowait
# SELECT * FROM items FOR UPDATE NOWAIT
    # File lib/sequel/dataset/query.rb
759 def nowait
760   return self if opts[:nowait]
761   cached_dataset(:_nowait_ds) do
762     raise(Error, 'This dataset does not support raises errors instead of waiting for locked rows') unless supports_nowait?
763     clone(:nowait=>true)
764   end
765 end
offset(o) click to toggle source

Returns a copy of the dataset with a specified order. Can be safely combined with limit. If you call limit with an offset, it will override the offset if you've called offset first.

DB[:items].offset(10) # SELECT * FROM items OFFSET 10
    # File lib/sequel/dataset/query.rb
772 def offset(o)
773   o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
774   if o.is_a?(Integer)
775     raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
776   end
777   clone(:offset => o)
778 end
or(*cond, &block) click to toggle source

Adds an alternate filter to an existing WHERE clause using OR. If there is no WHERE clause, then the default is WHERE true, and OR would be redundant, so return the dataset in that case.

DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b
DB[:items].or(:b) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
786 def or(*cond, &block)
787   if @opts[:where].nil?
788     self
789   else
790     add_filter(:where, cond, false, :OR, &block)
791   end
792 end
order(*columns, &block) click to toggle source

Returns a copy of the dataset with the order changed. If the dataset has an existing order, it is ignored and overwritten with this order. If a nil is given the returned dataset has no order. This can accept multiple arguments of varying kinds, such as SQL functions. If a block is given, it is treated as a virtual row block, similar to where.

DB[:items].order(:name) # SELECT * FROM items ORDER BY name
DB[:items].order(:a, :b) # SELECT * FROM items ORDER BY a, b
DB[:items].order(Sequel.lit('a + b')) # SELECT * FROM items ORDER BY a + b
DB[:items].order(Sequel[:a] + :b) # SELECT * FROM items ORDER BY (a + b)
DB[:items].order(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name DESC
DB[:items].order(Sequel.asc(:name, nulls: :last)) # SELECT * FROM items ORDER BY name ASC NULLS LAST
DB[:items].order{sum(name).desc} # SELECT * FROM items ORDER BY sum(name) DESC
DB[:items].order(nil) # SELECT * FROM items
    # File lib/sequel/dataset/query.rb
808 def order(*columns, &block)
809   virtual_row_columns(columns, block)
810   clone(:order => (columns.compact.empty?) ? nil : columns.freeze)
811 end
order_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the end of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_append(:b) # SELECT * FROM items ORDER BY a, b
    # File lib/sequel/dataset/query.rb
818 def order_append(*columns, &block)
819   columns = @opts[:order] + columns if @opts[:order]
820   order(*columns, &block)
821 end
order_by(*columns, &block) click to toggle source

Alias of order

    # File lib/sequel/dataset/query.rb
824 def order_by(*columns, &block)
825   order(*columns, &block)
826 end
order_more(*columns, &block) click to toggle source

Alias of order_append.

    # File lib/sequel/dataset/query.rb
829 def order_more(*columns, &block)
830   order_append(*columns, &block)
831 end
order_prepend(*columns, &block) click to toggle source

Returns a copy of the dataset with the order columns added to the beginning of the existing order.

DB[:items].order(:a).order(:b) # SELECT * FROM items ORDER BY b
DB[:items].order(:a).order_prepend(:b) # SELECT * FROM items ORDER BY b, a
    # File lib/sequel/dataset/query.rb
838 def order_prepend(*columns, &block)
839   ds = order(*columns, &block)
840   @opts[:order] ? ds.order_append(*@opts[:order]) : ds
841 end
qualify(table=(cache=true; first_source)) click to toggle source

Qualify to the given table, or first source if no table is given.

DB[:items].where(id: 1).qualify
# SELECT items.* FROM items WHERE (items.id = 1)

DB[:items].where(id: 1).qualify(:i)
# SELECT i.* FROM items WHERE (i.id = 1)
    # File lib/sequel/dataset/query.rb
850 def qualify(table=(cache=true; first_source))
851   o = @opts
852   return self if o[:sql]
853 
854   pr = proc do
855     h = {}
856     (o.keys & QUALIFY_KEYS).each do |k|
857       h[k] = qualified_expression(o[k], table)
858     end
859     h[:select] = [SQL::ColumnAll.new(table)].freeze if !o[:select] || o[:select].empty?
860     clone(h)
861   end
862 
863   cache ? cached_dataset(:_qualify_ds, &pr) : pr.call
864 end
returning(*values) click to toggle source

Modify the RETURNING clause, only supported on a few databases. If returning is used, instead of insert returning the autogenerated primary key or update/delete returning the number of modified rows, results are returned using fetch_rows.

DB[:items].returning # RETURNING *
DB[:items].returning(nil) # RETURNING NULL
DB[:items].returning(:id, :name) # RETURNING id, name

DB[:items].returning.insert(a: 1) do |hash|
  # hash for each row inserted, with values for all columns
end
DB[:items].returning.update(a: 1) do |hash|
  # hash for each row updated, with values for all columns
end
DB[:items].returning.delete(a: 1) do |hash|
  # hash for each row deleted, with values for all columns
end
    # File lib/sequel/dataset/query.rb
884 def returning(*values)
885   if values.empty?
886     return self if opts[:returning] == EMPTY_ARRAY
887     cached_dataset(:_returning_ds) do
888       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
889       clone(:returning=>EMPTY_ARRAY)
890     end
891   else
892     raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
893     clone(:returning=>values.freeze)
894   end
895 end
reverse(*order, &block) click to toggle source

Returns a copy of the dataset with the order reversed. If no order is given, the existing order is inverted.

DB[:items].reverse(:id) # SELECT * FROM items ORDER BY id DESC
DB[:items].reverse{foo(bar)} # SELECT * FROM items ORDER BY foo(bar) DESC
DB[:items].order(:id).reverse # SELECT * FROM items ORDER BY id DESC
DB[:items].order(:id).reverse(Sequel.desc(:name)) # SELECT * FROM items ORDER BY name ASC
    # File lib/sequel/dataset/query.rb
904 def reverse(*order, &block)
905   if order.empty? && !block
906     cached_dataset(:_reverse_ds){order(*invert_order(@opts[:order]))}
907   else
908     virtual_row_columns(order, block)
909     order(*invert_order(order.empty? ? @opts[:order] : order.freeze))
910   end
911 end
reverse_order(*order, &block) click to toggle source

Alias of reverse

    # File lib/sequel/dataset/query.rb
914 def reverse_order(*order, &block)
915   reverse(*order, &block)
916 end
select(*columns, &block) click to toggle source

Returns a copy of the dataset with the columns selected changed to the given columns. This also takes a virtual row block, similar to where.

DB[:items].select(:a) # SELECT a FROM items
DB[:items].select(:a, :b) # SELECT a, b FROM items
DB[:items].select{[a, sum(b)]} # SELECT a, sum(b) FROM items
    # File lib/sequel/dataset/query.rb
925 def select(*columns, &block)
926   virtual_row_columns(columns, block)
927   clone(:select => columns.freeze)
928 end
select_all(*tables) click to toggle source

Returns a copy of the dataset selecting the wildcard if no arguments are given. If arguments are given, treat them as tables and select all columns (using the wildcard) from each table.

DB[:items].select(:a).select_all # SELECT * FROM items
DB[:items].select_all(:items) # SELECT items.* FROM items
DB[:items].select_all(:items, :foo) # SELECT items.*, foo.* FROM items
    # File lib/sequel/dataset/query.rb
937 def select_all(*tables)
938   if tables.empty?
939     return self unless opts[:select]
940     cached_dataset(:_select_all_ds){clone(:select => nil)}
941   else
942     select(*tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze)
943   end
944 end
select_append(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.

DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_append(:b) # SELECT a, b FROM items
DB[:items].select_append(:b) # SELECT *, b FROM items
    # File lib/sequel/dataset/query.rb
953 def select_append(*columns, &block)
954   virtual_row_columns(columns, block)
955   select(*(_current_select(true) + columns))
956 end
select_group(*columns, &block) click to toggle source

Set both the select and group clauses with the given columns. Column aliases may be supplied, and will be included in the select clause. This also takes a virtual row block similar to where.

DB[:items].select_group(:a, :b)
# SELECT a, b FROM items GROUP BY a, b

DB[:items].select_group(Sequel[:c].as(:a)){f(c2)}
# SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)
    # File lib/sequel/dataset/query.rb
967 def select_group(*columns, &block)
968   virtual_row_columns(columns, block)
969   select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
970 end
select_more(*columns, &block) click to toggle source

Alias for select_append.

    # File lib/sequel/dataset/query.rb
973 def select_more(*columns, &block)
974   select_append(*columns, &block)
975 end
select_prepend(*columns, &block) click to toggle source

Returns a copy of the dataset with the given columns added to the existing selected columns. If no columns are currently selected, it will select the columns given in addition to *.

DB[:items].select(:a).select(:b) # SELECT b FROM items
DB[:items].select(:a).select_prepend(:b) # SELECT b, a FROM items
DB[:items].select_prepend(:b) # SELECT b, * FROM items
    # File lib/sequel/dataset/query.rb
984 def select_prepend(*columns, &block)
985   virtual_row_columns(columns, block)
986   select(*(columns + _current_select(false)))
987 end
server(servr) click to toggle source

Set the server for this dataset to use. Used to pick a specific database shard to run a query against, or to override the default (where SELECT uses :read_only database and all other queries use the :default database). This method is always available but is only useful when database sharding is being used.

DB[:items].all # Uses the :read_only or :default server
DB[:items].delete # Uses the :default server
DB[:items].server(:blah).delete # Uses the :blah server
     # File lib/sequel/dataset/query.rb
 998 def server(servr)
 999   clone(:server=>servr)
1000 end
server?(server) click to toggle source

If the database uses sharding and the current dataset has not had a server set, return a cloned dataset that uses the given server. Otherwise, return the receiver directly instead of returning a clone.

     # File lib/sequel/dataset/query.rb
1005 def server?(server)
1006   if db.sharded? && !opts[:server]
1007     server(server)
1008   else
1009     self
1010   end
1011 end
skip_limit_check() click to toggle source

Specify that the check for limits/offsets when updating/deleting be skipped for the dataset.

     # File lib/sequel/dataset/query.rb
1014 def skip_limit_check
1015   return self if opts[:skip_limit_check]
1016   cached_dataset(:_skip_limit_check_ds) do
1017     clone(:skip_limit_check=>true)
1018   end
1019 end
skip_locked() click to toggle source

Skip locked rows when returning results from this dataset.

     # File lib/sequel/dataset/query.rb
1022 def skip_locked
1023   return self if opts[:skip_locked]
1024   cached_dataset(:_skip_locked_ds) do
1025     raise(Error, 'This dataset does not support skipping locked rows') unless supports_skip_locked?
1026     clone(:skip_locked=>true)
1027   end
1028 end
unfiltered() click to toggle source

Returns a copy of the dataset with no filters (HAVING or WHERE clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).unfiltered
# SELECT * FROM items GROUP BY a
     # File lib/sequel/dataset/query.rb
1034 def unfiltered
1035   return self unless opts[:where] || opts[:having]
1036   cached_dataset(:_unfiltered_ds){clone(:where => nil, :having => nil)}
1037 end
ungrouped() click to toggle source

Returns a copy of the dataset with no grouping (GROUP or HAVING clause) applied.

DB[:items].group(:a).having(a: 1).where(:b).ungrouped
# SELECT * FROM items WHERE b
     # File lib/sequel/dataset/query.rb
1043 def ungrouped
1044   return self unless opts[:group] || opts[:having]
1045   cached_dataset(:_ungrouped_ds){clone(:group => nil, :having => nil)}
1046 end
union(dataset, opts=OPTS) click to toggle source

Adds a UNION clause using a second dataset object. A UNION compound dataset returns all rows in either the current dataset or the given dataset. Options:

:alias

Use the given value as the from_self alias

:all

Set to true to use UNION ALL instead of UNION, so duplicate rows can occur

:from_self

Set to false to not wrap the returned dataset in a from_self, use with care.

DB[:items].union(DB[:other_items])
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS t1

DB[:items].union(DB[:other_items], all: true, from_self: false)
# SELECT * FROM items UNION ALL SELECT * FROM other_items

DB[:items].union(DB[:other_items], alias: :i)
# SELECT * FROM (SELECT * FROM items UNION SELECT * FROM other_items) AS i
     # File lib/sequel/dataset/query.rb
1064 def union(dataset, opts=OPTS)
1065   compound_clone(:union, dataset, opts)
1066 end
unlimited() click to toggle source

Returns a copy of the dataset with no limit or offset.

DB[:items].limit(10, 20).unlimited # SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1071 def unlimited
1072   return self unless opts[:limit] || opts[:offset]
1073   cached_dataset(:_unlimited_ds){clone(:limit=>nil, :offset=>nil)}
1074 end
unordered() click to toggle source

Returns a copy of the dataset with no order.

DB[:items].order(:a).unordered # SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1079 def unordered
1080   return self unless opts[:order]
1081   cached_dataset(:_unordered_ds){clone(:order=>nil)}
1082 end
where(*cond, &block) click to toggle source

Returns a copy of the dataset with the given WHERE conditions imposed upon it.

Accepts the following argument types:

Hash, Array of pairs

list of equality/inclusion expressions

Symbol

taken as a boolean column argument (e.g. WHERE active)

Sequel::SQL::BooleanExpression, Sequel::LiteralString

an existing condition expression, probably created using the Sequel expression filter DSL.

where also accepts a block, which should return one of the above argument types, and is treated the same way. This block yields a virtual row object, which is easy to use to create identifiers and functions. For more details on the virtual row support, see the “Virtual Rows” guide

If both a block and regular argument are provided, they get ANDed together.

Examples:

DB[:items].where(id: 3)
# SELECT * FROM items WHERE (id = 3)

DB[:items].where(Sequel.lit('price < ?', 100))
# SELECT * FROM items WHERE price < 100

DB[:items].where([[:id, [1,2,3]], [:id, 0..10]])
# SELECT * FROM items WHERE ((id IN (1, 2, 3)) AND ((id >= 0) AND (id <= 10)))

DB[:items].where(Sequel.lit('price < 100'))
# SELECT * FROM items WHERE price < 100

DB[:items].where(:active)
# SELECT * FROM items WHERE :active

DB[:items].where{price < 100}
# SELECT * FROM items WHERE (price < 100)

Multiple where calls can be chained for scoping:

software = dataset.where(category: 'software').where{price < 100}
# SELECT * FROM items WHERE ((category = 'software') AND (price < 100))

See the “Dataset Filtering” guide for more examples and details.

     # File lib/sequel/dataset/query.rb
1126 def where(*cond, &block)
1127   add_filter(:where, cond, &block)
1128 end
window(name, opts) click to toggle source

Return a clone of the dataset with an addition named window that can be referenced in window functions. See Sequel::SQL::Window for a list of options that can be passed in. Example:

DB[:items].window(:w, partition: :c1, order: :c2)
# SELECT * FROM items WINDOW w AS (PARTITION BY c1 ORDER BY c2)
     # File lib/sequel/dataset/query.rb
1136 def window(name, opts)
1137   clone(:window=>((@opts[:window]||EMPTY_ARRAY) + [[name, SQL::Window.new(opts)].freeze]).freeze)
1138 end
with(name, dataset, opts=OPTS) click to toggle source

Add a common table expression (CTE) with the given name and a dataset that defines the CTE. A common table expression acts as an inline view for the query.

Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:recursive

Specify that this is a recursive CTE

:materialized

Set to false to force inlining of the CTE, or true to force not inlining the CTE (PostgreSQL 12+/SQLite 3.35+).

DB[:items].with(:items, DB[:syx].where(Sequel[:name].like('A%')))
# WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%' ESCAPE '\')) SELECT * FROM items
     # File lib/sequel/dataset/query.rb
1151 def with(name, dataset, opts=OPTS)
1152   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1153   if hoist_cte?(dataset)
1154     s, ds = hoist_cte(dataset)
1155     s.with(name, ds, opts)
1156   else
1157     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:name=>name, :dataset=>dataset)]).freeze)
1158   end
1159 end
with_extend(*mods, &block) click to toggle source

Create a subclass of the receiver's class, and include the given modules into it. If a block is provided, a DatasetModule is created using the block and is included into the subclass. Create an instance of the subclass using the same db and opts, so that the returned dataset operates similarly to a clone extended with the given modules. This approach is used to avoid singleton classes, which significantly improves performance.

Note that like Object#extend, when multiple modules are provided as arguments the subclass includes the modules in reverse order.

     # File lib/sequel/dataset/query.rb
1240 def with_extend(*mods, &block)
1241   c = Class.new(self.class)
1242   c.include(*mods) unless mods.empty?
1243   c.include(DatasetModule.new(&block)) if block
1244   o = c.freeze.allocate
1245   o.instance_variable_set(:@db, @db)
1246   o.instance_variable_set(:@opts, @opts)
1247   o.instance_variable_set(:@cache, {})
1248   if cols = cache_get(:_columns)
1249     o.send(:columns=, cols)
1250   end
1251   o.freeze
1252 end
with_recursive(name, nonrecursive, recursive, opts=OPTS) click to toggle source

Add a recursive common table expression (CTE) with the given name, a dataset that defines the nonrecursive part of the CTE, and a dataset that defines the recursive part of the CTE.

Options:

:args

Specify the arguments/columns for the CTE, should be an array of symbols.

:union_all

Set to false to use UNION instead of UNION ALL combining the nonrecursive and recursive parts.

PostgreSQL 14+ Options:

:cycle

Stop recursive searching when a cycle is detected. Includes two columns in the result of the CTE, a cycle column indicating whether a cycle was detected for the current row, and a path column for the path traversed to get to the current row. If given, must be a hash with the following keys:

:columns

(required) The column or array of columns to use to detect a cycle. If the value of these columns match columns already traversed, then a cycle is detected, and recursive searching will not traverse beyond the cycle (the CTE will include the row where the cycle was detected).

:cycle_column

The name of the cycle column in the output, defaults to :is_cycle.

:cycle_value

The value of the cycle column in the output if the current row was detected as a cycle, defaults to true.

:noncycle_value

The value of the cycle column in the output if the current row was not detected as a cycle, defaults to false. Only respected if :cycle_value is given.

:path_column

The name of the path column in the output, defaults to :path.

:search

Include an order column in the result of the CTE that allows for breadth or depth first searching. If given, must be a hash with the following keys:

:by

(required) The column or array of columns to search by.

:order_column

The name of the order column in the output, defaults to :ordercol.

:type

Set to :breadth to use breadth-first searching (depth-first searching is the default).

DB[:t].with_recursive(:t,
  DB[:i1].select(:id, :parent_id).where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select(Sequel[:i1][:id], Sequel[:i1][:parent_id]),
  args: [:id, :parent_id])

# WITH RECURSIVE t(id, parent_id) AS (
#   SELECT id, parent_id FROM i1 WHERE (parent_id IS NULL)
#   UNION ALL
#   SELECT i1.id, i1.parent_id FROM i1 INNER JOIN t ON (t.id = i1.parent_id)
# ) SELECT * FROM t

DB[:t].with_recursive(:t,
  DB[:i1].where(parent_id: nil),
  DB[:i1].join(:t, id: :parent_id).select_all(:i1),
  search: {by: :id, type: :breadth},
  cycle: {columns: :id, cycle_value: 1, noncycle_value: 2})

# WITH RECURSIVE t AS (
#     SELECT * FROM i1 WHERE (parent_id IS NULL)
#     UNION ALL
#     (SELECT i1.* FROM i1 INNER JOIN t ON (t.id = i1.parent_id))
#   )
#   SEARCH BREADTH FIRST BY id SET ordercol
#   CYCLE id SET is_cycle TO 1 DEFAULT 2 USING path
# SELECT * FROM t
     # File lib/sequel/dataset/query.rb
1217 def with_recursive(name, nonrecursive, recursive, opts=OPTS)
1218   raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
1219   if hoist_cte?(nonrecursive)
1220     s, ds = hoist_cte(nonrecursive)
1221     s.with_recursive(name, ds, recursive, opts)
1222   elsif hoist_cte?(recursive)
1223     s, ds = hoist_cte(recursive)
1224     s.with_recursive(name, nonrecursive, ds, opts)
1225   else
1226     clone(:with=>((@opts[:with]||EMPTY_ARRAY) + [Hash[opts].merge!(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))]).freeze)
1227   end
1228 end
with_row_proc(callable) click to toggle source

Returns a cloned dataset with the given row_proc.

ds = DB[:items]
ds.all # => [{:id=>2}]
ds.with_row_proc(:invert.to_proc).all # => [{2=>:id}]
     # File lib/sequel/dataset/query.rb
1269 def with_row_proc(callable)
1270   clone(:row_proc=>callable)
1271 end
with_sql(sql, *args) click to toggle source

Returns a copy of the dataset with the static SQL used. This is useful if you want to keep the same row_proc/graph, but change the SQL used to custom SQL.

DB[:items].with_sql('SELECT * FROM foo') # SELECT * FROM foo

You can use placeholders in your SQL and provide arguments for those placeholders:

DB[:items].with_sql('SELECT ? FROM foo', 1) # SELECT 1 FROM foo

You can also provide a method name and arguments to call to get the SQL:

DB[:items].with_sql(:insert_sql, b: 1) # INSERT INTO items (b) VALUES (1)

Note that datasets that specify custom SQL using this method will generally ignore future dataset methods that modify the SQL used, as specifying custom SQL overrides Sequel's SQL generator. You should probably limit yourself to the following dataset methods when using this method, or use the implicit_subquery extension:

  • each

  • all

  • single_record (if only one record could be returned)

  • single_value (if only one record could be returned, and a single column is selected)

  • map

  • as_hash

  • to_hash

  • to_hash_groups

  • delete (if a DELETE statement)

  • update (if an UPDATE statement, with no arguments)

  • insert (if an INSERT statement, with no arguments)

  • truncate (if a TRUNCATE statement, with no arguments)

     # File lib/sequel/dataset/query.rb
1303 def with_sql(sql, *args)
1304   if sql.is_a?(Symbol)
1305     sql = public_send(sql, *args)
1306   else
1307     sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
1308   end
1309   clone(:sql=>sql)
1310 end

Protected Instance Methods

compound_clone(type, dataset, opts) click to toggle source

Add the dataset to the list of compounds

     # File lib/sequel/dataset/query.rb
1315 def compound_clone(type, dataset, opts)
1316   if dataset.is_a?(Dataset) && dataset.opts[:with] && !supports_cte_in_compounds?
1317     s, ds = hoist_cte(dataset)
1318     return s.compound_clone(type, ds, opts)
1319   end
1320   ds = compound_from_self.clone(:compounds=>(Array(@opts[:compounds]).map(&:dup) + [[type, dataset.compound_from_self, opts[:all]].freeze]).freeze)
1321   opts[:from_self] == false ? ds : ds.from_self(opts)
1322 end
options_overlap(opts) click to toggle source

Return true if the dataset has a non-nil value for any key in opts.

     # File lib/sequel/dataset/query.rb
1325 def options_overlap(opts)
1326   !(@opts.map{|k,v| k unless v.nil?}.compact & opts).empty?
1327 end
simple_select_all?() click to toggle source

Whether this dataset is a simple select from an underlying table, such as:

SELECT * FROM table
SELECT table.* FROM table
     # File lib/sequel/dataset/query.rb
1336 def simple_select_all?
1337   return false unless (f = @opts[:from]) && f.length == 1
1338   o = @opts.reject{|k,v| v.nil? || non_sql_option?(k)}
1339   from = f.first
1340   from = from.expression if from.is_a?(SQL::AliasedExpression)
1341 
1342   if SIMPLE_SELECT_ALL_ALLOWED_FROM.any?{|x| from.is_a?(x)}
1343     case o.length
1344     when 1
1345       true
1346     when 2
1347       (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1348     else
1349       false
1350     end
1351   else
1352     false
1353   end
1354 end

Private Instance Methods

_current_select(allow_plain_wildcard) click to toggle source

A frozen array for the currently selected columns.

     # File lib/sequel/dataset/query.rb
1380 def _current_select(allow_plain_wildcard)
1381   cur_sel = @opts[:select]
1382 
1383   if !cur_sel || cur_sel.empty?
1384     cur_sel = if allow_plain_wildcard && supports_select_all_and_column?
1385       [WILDCARD].freeze
1386     else
1387       _current_select_column_all
1388     end
1389   elsif !allow_plain_wildcard && cur_sel.include?(WILDCARD)
1390     cur_sel = cur_sel.dup
1391     index = cur_sel.index(WILDCARD)
1392     cur_sel.delete(WILDCARD)
1393     _current_select_column_all.each_with_index do |ca, i|
1394       cur_sel.insert(index+i, ca)
1395     end
1396     cur_sel.freeze
1397   end
1398 
1399   cur_sel
1400 end
_current_select_column_all() click to toggle source

An array of SQL::ColumnAll objects for all FROM and JOIN tables. Used for select_append and select_prepend.

     # File lib/sequel/dataset/query.rb
1404 def _current_select_column_all
1405   tables = Array(@opts[:from]) + Array(@opts[:join])
1406   tables.map{|t| i, a = split_alias(t); a || i}.map!{|t| SQL::ColumnAll.new(t)}.freeze
1407 end
_extension!(exts) click to toggle source

Load the extensions into the receiver, without checking if the receiver is frozen.

     # File lib/sequel/dataset/query.rb
1361 def _extension!(exts)
1362   exts.each do |ext|
1363     unless pr = Sequel.synchronize{EXTENSIONS[ext]}
1364       Sequel.extension(ext)
1365       pr = Sequel.synchronize{EXTENSIONS[ext]}
1366     end
1367 
1368     if pr
1369       pr.call(self)
1370     else
1371       raise(Error, "Extension #{ext} does not have specific support handling individual datasets (try: Sequel.extension #{ext.inspect})")
1372     end
1373   end
1374   self
1375 end
_invert_filter(cond, invert) click to toggle source

If invert is true, invert the condition.

     # File lib/sequel/dataset/query.rb
1410 def _invert_filter(cond, invert)
1411   if invert
1412     SQL::BooleanExpression.invert(cond)
1413   else
1414     cond
1415   end
1416 end
_merge_when(hash, &block) click to toggle source

Append to the current MERGE WHEN clauses. Mutates the hash to add the conditions, if a virtual row block is passed.

     # File lib/sequel/dataset/query.rb
1420 def _merge_when(hash, &block)
1421   hash[:conditions] = Sequel.virtual_row(&block) if block
1422 
1423   if merge_when = @opts[:merge_when]
1424     clone(:merge_when => (merge_when.dup << hash.freeze).freeze)
1425   else
1426     clone(:merge_when => [hash.freeze].freeze)
1427   end
1428 end
add_filter(clause, cond, invert=false, combine=:AND, &block) click to toggle source

Add the given filter condition. Arguments:

clause

Symbol or which SQL clause to effect, should be :where or :having

cond

The filter condition to add

invert

Whether the condition should be inverted (true or false)

combine

How to combine the condition with an existing condition, should be :AND or :OR

     # File lib/sequel/dataset/query.rb
1435 def add_filter(clause, cond, invert=false, combine=:AND, &block)
1436   if cond == EMPTY_ARRAY && !block
1437     raise Error, "must provide an argument to a filtering method if not passing a block"
1438   end
1439   
1440   cond = cond.first if cond.size == 1
1441 
1442   empty = cond == OPTS || cond == EMPTY_ARRAY
1443 
1444   if empty && !block
1445     self 
1446   else
1447     if cond == nil
1448       cond = Sequel::NULL
1449     end
1450     if empty && block
1451       cond = nil
1452     end
1453 
1454     cond = _invert_filter(filter_expr(cond, &block), invert)
1455     cond = SQL::BooleanExpression.new(combine, @opts[clause], cond) if @opts[clause]
1456 
1457     if cond.nil?
1458       cond = Sequel::NULL
1459     end
1460 
1461     clone(clause => cond)
1462   end
1463 end
default_join_table_qualification() click to toggle source

The default :qualify option to use for join tables if one is not specified.

     # File lib/sequel/dataset/query.rb
1466 def default_join_table_qualification
1467   :symbol
1468 end
default_server() click to toggle source

Return self if the dataset already has a server, or a cloned dataset with the default server otherwise.

     # File lib/sequel/dataset/query.rb
1541 def default_server
1542   server?(:default)
1543 end
filter_expr(expr = nil, &block) click to toggle source

SQL expression object based on the expr type. See where.

     # File lib/sequel/dataset/query.rb
1471 def filter_expr(expr = nil, &block)
1472   expr = nil if expr == EMPTY_ARRAY
1473 
1474   if block
1475     cond = filter_expr(Sequel.virtual_row(&block))
1476     cond = SQL::BooleanExpression.new(:AND, filter_expr(expr), cond) if expr
1477     return cond
1478   end
1479 
1480   case expr
1481   when Hash
1482     SQL::BooleanExpression.from_value_pairs(expr)
1483   when Array
1484     if Sequel.condition_specifier?(expr)
1485       SQL::BooleanExpression.from_value_pairs(expr)
1486     else
1487       raise Error, "Invalid filter expression: #{expr.inspect}"
1488     end
1489   when LiteralString
1490     LiteralString.new("(#{expr})")
1491   when Numeric, SQL::NumericExpression, SQL::StringExpression, Proc, String
1492     raise Error, "Invalid filter expression: #{expr.inspect}"
1493   when TrueClass, FalseClass
1494     if supports_where_true?
1495       SQL::BooleanExpression.new(:NOOP, expr)
1496     elsif expr
1497       SQL::Constants::SQLTRUE
1498     else
1499       SQL::Constants::SQLFALSE
1500     end
1501   when PlaceholderLiteralizer::Argument
1502     expr.transform{|v| filter_expr(v)}
1503   when SQL::PlaceholderLiteralString
1504     expr.with_parens
1505   else
1506     expr
1507   end
1508 end
hoist_cte(ds) click to toggle source

Return two datasets, the first a clone of the receiver with the WITH clause from the given dataset added to it, and the second a clone of the given dataset with the WITH clause removed.

     # File lib/sequel/dataset/query.rb
1513 def hoist_cte(ds)
1514   [clone(:with => ((opts[:with] || EMPTY_ARRAY) + ds.opts[:with]).freeze), ds.clone(:with => nil)]
1515 end
hoist_cte?(ds) click to toggle source

Whether CTEs need to be hoisted from the given ds into the current ds.

     # File lib/sequel/dataset/query.rb
1518 def hoist_cte?(ds)
1519   ds.is_a?(Dataset) && ds.opts[:with] && !supports_cte_in_subqueries?
1520 end
invert_order(order) click to toggle source

Inverts the given order by breaking it into a list of column references and inverting them.

DB[:items].invert_order([Sequel.desc(:id)]]) #=> [Sequel.asc(:id)]
DB[:items].invert_order([:category, Sequel.desc(:price)]) #=> [Sequel.desc(:category), Sequel.asc(:price)]
     # File lib/sequel/dataset/query.rb
1527 def invert_order(order)
1528   return unless order
1529   order.map do |f|
1530     case f
1531     when SQL::OrderedExpression
1532       f.invert
1533     else
1534       SQL::OrderedExpression.new(f)
1535     end
1536   end
1537 end
non_sql_option?(key) click to toggle source

Whether the given option key does not affect the generated SQL.

     # File lib/sequel/dataset/query.rb
1546 def non_sql_option?(key)
1547   NON_SQL_OPTIONS.include?(key)
1548 end
virtual_row_columns(columns, block) click to toggle source

Treat the block as a virtual_row block if not nil and add the resulting columns to the columns array (modifies columns).

     # File lib/sequel/dataset/query.rb
1552 def virtual_row_columns(columns, block)
1553   if block
1554     v = Sequel.virtual_row(&block)
1555     if v.is_a?(Array)
1556       columns.concat(v)
1557     else
1558       columns << v
1559     end
1560   end
1561 end

2 - Methods that execute code on the database

↑ top

Constants

ACTION_METHODS

Action methods defined by Sequel that execute code on the database.

COLUMNS_CLONE_OPTIONS

The clone options to use when retrieving columns for a dataset.

COUNT_SELECT
EMPTY_SELECT

Public Instance Methods

<<(arg) click to toggle source

Inserts the given argument into the database. Returns self so it can be used safely when chaining:

DB[:items] << {id: 0, name: 'Zero'} << DB[:old_items].select(:id, name)
   # File lib/sequel/dataset/actions.rb
28 def <<(arg)
29   insert(arg)
30   self
31 end
[](*conditions) click to toggle source

Returns the first record matching the conditions. Examples:

DB[:table][id: 1] # SELECT * FROM table WHERE (id = 1) LIMIT 1
# => {:id=>1}
   # File lib/sequel/dataset/actions.rb
37 def [](*conditions)
38   raise(Error, 'You cannot call Dataset#[] with an integer or with no arguments') if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
39   first(*conditions)
40 end
all(&block) click to toggle source

Returns an array with all records in the dataset. If a block is given, the array is iterated over after all items have been loaded.

DB[:table].all # SELECT * FROM table
# => [{:id=>1, ...}, {:id=>2, ...}, ...]

# Iterate over all rows in the table
DB[:table].all{|row| p row}
   # File lib/sequel/dataset/actions.rb
50 def all(&block)
51   _all(block){|a| each{|r| a << r}}
52 end
as_hash(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and another used as value. If rows have duplicate values for the key column, the latter row(s) will overwrite the value of the previous row(s). If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].as_hash(:id, :name) # SELECT * FROM table
# {1=>'Jim', 2=>'Bob', ...}

DB[:table].as_hash(:id) # SELECT * FROM table
# {1=>{:id=>1, :name=>'Jim'}, 2=>{:id=>2, :name=>'Bob'}, ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].as_hash([:id, :foo], [:name, :bar]) # SELECT * FROM table
# {[1, 3]=>['Jim', 'bo'], [2, 4]=>['Bob', 'be'], ...}

DB[:table].as_hash([:id, :name]) # SELECT * FROM table
# {[1, 'Jim']=>{:id=>1, :name=>'Jim'}, [2, 'Bob']=>{:id=>2, :name=>'Bob'}, ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
855 def as_hash(key_column, value_column = nil, opts = OPTS)
856   h = opts[:hash] || {}
857   meth = opts[:all] ? :all : :each
858   if value_column
859     return naked.as_hash(key_column, value_column, opts) if row_proc
860     if value_column.is_a?(Array)
861       if key_column.is_a?(Array)
862         public_send(meth){|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
863       else
864         public_send(meth){|r| h[r[key_column]] = r.values_at(*value_column)}
865       end
866     else
867       if key_column.is_a?(Array)
868         public_send(meth){|r| h[r.values_at(*key_column)] = r[value_column]}
869       else
870         public_send(meth){|r| h[r[key_column]] = r[value_column]}
871       end
872     end
873   elsif key_column.is_a?(Array)
874     public_send(meth){|r| h[key_column.map{|k| r[k]}] = r}
875   else
876     public_send(meth){|r| h[r[key_column]] = r}
877   end
878   h
879 end
avg(arg=(no_arg = true), &block) click to toggle source

Returns the average value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].avg(:number) # SELECT avg(number) FROM table LIMIT 1
# => 3
DB[:table].avg{function(column)} # SELECT avg(function(column)) FROM table LIMIT 1
# => 1
   # File lib/sequel/dataset/actions.rb
61 def avg(arg=(no_arg = true), &block)
62   arg = Sequel.virtual_row(&block) if no_arg
63   _aggregate(:avg, arg)
64 end
columns() click to toggle source

Returns the columns in the result set in order as an array of symbols. If the columns are currently cached, returns the cached value. Otherwise, a SELECT query is performed to retrieve a single row in order to get the columns.

If you are looking for all columns for a single table and maybe some information about each column (e.g. database type), see Database#schema.

DB[:table].columns
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
75 def columns
76   _columns || columns!
77 end
columns!() click to toggle source

Ignore any cached column information and perform a query to retrieve a row in order to get the columns.

DB[:table].columns!
# => [:id, :name]
   # File lib/sequel/dataset/actions.rb
84 def columns!
85   ds = clone(COLUMNS_CLONE_OPTIONS)
86   ds.each{break}
87 
88   if cols = ds.cache[:_columns]
89     self.columns = cols
90   else
91     []
92   end
93 end
count(arg=(no_arg=true), &block) click to toggle source

Returns the number of records in the dataset. If an argument is provided, it is used as the argument to count. If a block is provided, it is treated as a virtual row, and the result is used as the argument to count.

DB[:table].count # SELECT count(*) AS count FROM table LIMIT 1
# => 3
DB[:table].count(:column) # SELECT count(column) AS count FROM table LIMIT 1
# => 2
DB[:table].count{foo(column)} # SELECT count(foo(column)) AS count FROM table LIMIT 1
# => 1
    # File lib/sequel/dataset/actions.rb
108 def count(arg=(no_arg=true), &block)
109   if no_arg && !block
110     cached_dataset(:_count_ds) do
111       aggregate_dataset.select(COUNT_SELECT).single_value_ds
112     end.single_value!.to_i
113   else
114     if block
115       if no_arg
116         arg = Sequel.virtual_row(&block)
117       else
118         raise Error, 'cannot provide both argument and block to Dataset#count'
119       end
120     end
121 
122     _aggregate(:count, arg)
123   end
124 end
delete(&block) click to toggle source

Deletes the records in the dataset, returning the number of records deleted.

DB[:table].delete # DELETE * FROM table
# => 3

Some databases support using multiple tables in a DELETE query. This requires multiple FROM tables (JOINs can also be used). As multiple FROM tables use an implicit CROSS JOIN, you should make sure your WHERE condition uses the appropriate filters for the FROM tables:

DB.from(:a, :b).join(:c, :d=>Sequel[:b][:e]).where{{a[:f]=>b[:g], a[:id]=>c[:h]}}.
  delete
# DELETE FROM a
# USING b
# INNER JOIN c ON (c.d = b.e)
# WHERE ((a.f = b.g) AND (a.id = c.h))
    # File lib/sequel/dataset/actions.rb
142 def delete(&block)
143   sql = delete_sql
144   if uses_returning?(:delete)
145     returning_fetch_rows(sql, &block)
146   else
147     execute_dui(sql)
148   end
149 end
each() { |call| ... } click to toggle source

Iterates over the records in the dataset as they are yielded from the database adapter, and returns self.

DB[:table].each{|row| p row} # SELECT * FROM table

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, you should use all instead of each for the outer queries, or use a separate thread or shard inside each.

    # File lib/sequel/dataset/actions.rb
160 def each
161   if rp = row_proc
162     fetch_rows(select_sql){|r| yield rp.call(r)}
163   else
164     fetch_rows(select_sql){|r| yield r}
165   end
166   self
167 end
empty?() click to toggle source

Returns true if no records exist in the dataset, false otherwise

DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
# => false
    # File lib/sequel/dataset/actions.rb
175 def empty?
176   cached_dataset(:_empty_ds) do
177     (@opts[:sql] ? from_self : self).single_value_ds.unordered.select(EMPTY_SELECT)
178   end.single_value!.nil?
179 end
first(*args, &block) click to toggle source

Returns the first matching record if no arguments are given. If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If any other type of argument(s) is passed, it is treated as a filter and the first matching record is returned. If a block is given, it is used to filter the dataset before returning anything.

If there are no records in the dataset, returns nil (or an empty array if an integer argument is given).

Examples:

DB[:table].first # SELECT * FROM table LIMIT 1
# => {:id=>7}

DB[:table].first(2) # SELECT * FROM table LIMIT 2
# => [{:id=>6}, {:id=>4}]

DB[:table].first(id: 2) # SELECT * FROM table WHERE (id = 2) LIMIT 1
# => {:id=>2}

DB[:table].first(Sequel.lit("id = 3")) # SELECT * FROM table WHERE (id = 3) LIMIT 1
# => {:id=>3}

DB[:table].first(Sequel.lit("id = ?", 4)) # SELECT * FROM table WHERE (id = 4) LIMIT 1
# => {:id=>4}

DB[:table].first{id > 2} # SELECT * FROM table WHERE (id > 2) LIMIT 1
# => {:id=>5}

DB[:table].first(Sequel.lit("id > ?", 4)){id < 6} # SELECT * FROM table WHERE ((id > 4) AND (id < 6)) LIMIT 1
# => {:id=>5}

DB[:table].first(2){id < 2} # SELECT * FROM table WHERE (id < 2) LIMIT 2
# => [{:id=>1}]
    # File lib/sequel/dataset/actions.rb
216 def first(*args, &block)
217   case args.length
218   when 0
219     unless block
220       return(@opts[:sql] ? single_record! : single_record)
221     end
222   when 1
223     arg = args[0]
224     if arg.is_a?(Integer)
225       res = if block
226         if loader = cached_placeholder_literalizer(:_first_integer_cond_loader) do |pl|
227             where(pl.arg).limit(pl.arg)
228           end
229 
230           loader.all(filter_expr(&block), arg)
231         else
232           where(&block).limit(arg).all
233         end
234       else
235         if loader = cached_placeholder_literalizer(:_first_integer_loader) do |pl|
236            limit(pl.arg)
237           end
238 
239           loader.all(arg)
240         else
241           limit(arg).all
242         end
243       end
244 
245       return res
246     end
247     where_args = args
248     args = arg
249   end
250 
251   if loader = cached_where_placeholder_literalizer(where_args||args, block, :_first_cond_loader) do |pl|
252       _single_record_ds.where(pl.arg)
253     end
254 
255     loader.first(filter_expr(args, &block))
256   else
257     _single_record_ds.where(args, &block).single_record!
258   end
259 end
first!(*args, &block) click to toggle source

Calls first. If first returns nil (signaling that no row matches), raise a Sequel::NoMatchingRow exception.

    # File lib/sequel/dataset/actions.rb
263 def first!(*args, &block)
264   first(*args, &block) || raise(Sequel::NoMatchingRow.new(self))
265 end
get(column=(no_arg=true; nil), &block) click to toggle source

Return the column value for the first matching record in the dataset. Raises an error if both an argument and block is given.

DB[:table].get(:id) # SELECT id FROM table LIMIT 1
# => 3

ds.get{sum(id)} # SELECT sum(id) AS v FROM table LIMIT 1
# => 6

You can pass an array of arguments to return multiple arguments, but you must make sure each element in the array has an alias that Sequel can determine:

DB[:table].get([:id, :name]) # SELECT id, name FROM table LIMIT 1
# => [3, 'foo']

DB[:table].get{[sum(id).as(sum), name]} # SELECT sum(id) AS sum, name FROM table LIMIT 1
# => [6, 'foo']

If called on a dataset with raw SQL, returns the first value in the dataset without changing the selection or setting a limit:

DB["SELECT id FROM table"].get # SELECT id FROM table
# =>  3
    # File lib/sequel/dataset/actions.rb
291 def get(column=(no_arg=true; nil), &block)
292   ds = naked
293   if block
294     raise(Error, 'Must call Dataset#get with an argument or a block, not both') unless no_arg
295     ds = ds.select(&block)
296     column = ds.opts[:select]
297     column = nil if column.is_a?(Array) && column.length < 2
298   elsif no_arg && opts[:sql]
299     return ds.single_value!
300   else
301     case column
302     when Array
303       ds = ds.select(*column)
304     when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
305       if loader = cached_placeholder_literalizer(:_get_loader) do |pl|
306           ds.single_value_ds.select(pl.arg)
307         end
308 
309         return loader.get(column)
310       end
311 
312       ds = ds.select(column)
313     else
314       if loader = cached_placeholder_literalizer(:_get_alias_loader) do |pl|
315           ds.single_value_ds.select(Sequel.as(pl.arg, :v))
316         end
317 
318         return loader.get(column)
319       end
320 
321       ds = ds.select(Sequel.as(column, :v))
322     end
323   end
324 
325   if column.is_a?(Array)
326    if r = ds.single_record
327      r.values_at(*hash_key_symbols(column))
328    end
329   else
330     ds.single_value
331   end
332 end
import(columns, values, opts=OPTS) click to toggle source

Inserts multiple records into the associated table. This method can be used to efficiently insert a large number of records into a table in a single query if the database supports it. Inserts are automatically wrapped in a transaction if necessary.

This method is called with a columns array and an array of value arrays:

DB[:table].import([:x, :y], [[1, 2], [3, 4]])
# INSERT INTO table (x, y) VALUES (1, 2)
# INSERT INTO table (x, y) VALUES (3, 4)

or, if the database supports it:

# INSERT INTO table (x, y) VALUES (1, 2), (3, 4)

This method also accepts a dataset instead of an array of value arrays:

DB[:table].import([:x, :y], DB[:table2].select(:a, :b))
# INSERT INTO table (x, y) SELECT a, b FROM table2

Options:

:commit_every

Open a new transaction for every given number of records. For example, if you provide a value of 50, will commit after every 50 records. When a transaction is not required, this option controls the maximum number of values to insert with a single statement; it does not force the use of a transaction.

:return

When this is set to :primary_key, returns an array of autoincremented primary key values for the rows inserted. This does not have an effect if values is a Dataset.

:server

Set the server/shard to use for the transaction and insert queries.

:skip_transaction

Do not use a transaction even when using multiple INSERT queries.

:slice

Same as :commit_every, :commit_every takes precedence.

    # File lib/sequel/dataset/actions.rb
370 def import(columns, values, opts=OPTS)
371   return insert(columns, values) if values.is_a?(Dataset)
372 
373   return if values.empty?
374   raise(Error, 'Using Sequel::Dataset#import with an empty column array is not allowed') if columns.empty?
375   ds = opts[:server] ? server(opts[:server]) : self
376   
377   if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
378     offset = 0
379     rows = []
380     while offset < values.length
381       rows << ds._import(columns, values[offset, slice_size], opts)
382       offset += slice_size
383     end
384     rows.flatten
385   else
386     ds._import(columns, values, opts)
387   end
388 end
insert(*values, &block) click to toggle source

Inserts values into the associated table. The returned value is generally the value of the autoincremented primary key for the inserted row, assuming that a single row is inserted and the table has an autoincrementing primary key.

insert handles a number of different argument formats:

no arguments or single empty hash

Uses DEFAULT VALUES

single hash

Most common format, treats keys as columns and values as values

single array

Treats entries as values, with no columns

two arrays

Treats first array as columns, second array as values

single Dataset

Treats as an insert based on a selection from the dataset given, with no columns

array and dataset

Treats as an insert based on a selection from the dataset given, with the columns given by the array.

Examples:

DB[:items].insert
# INSERT INTO items DEFAULT VALUES

DB[:items].insert({})
# INSERT INTO items DEFAULT VALUES

DB[:items].insert([1,2,3])
# INSERT INTO items VALUES (1, 2, 3)

DB[:items].insert([:a, :b], [1,2])
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(a: 1, b: 2)
# INSERT INTO items (a, b) VALUES (1, 2)

DB[:items].insert(DB[:old_items])
# INSERT INTO items SELECT * FROM old_items

DB[:items].insert([:a, :b], DB[:old_items])
# INSERT INTO items (a, b) SELECT * FROM old_items
    # File lib/sequel/dataset/actions.rb
426 def insert(*values, &block)
427   sql = insert_sql(*values)
428   if uses_returning?(:insert)
429     returning_fetch_rows(sql, &block)
430   else
431     execute_insert(sql)
432   end
433 end
last(*args, &block) click to toggle source

Reverses the order and then runs first with the given arguments and block. Note that this will not necessarily give you the last record in the dataset, unless you have an unambiguous order. If there is not currently an order for this dataset, raises an Error.

DB[:table].order(:id).last # SELECT * FROM table ORDER BY id DESC LIMIT 1
# => {:id=>10}

DB[:table].order(Sequel.desc(:id)).last(2) # SELECT * FROM table ORDER BY id ASC LIMIT 2
# => [{:id=>1}, {:id=>2}]
    # File lib/sequel/dataset/actions.rb
445 def last(*args, &block)
446   raise(Error, 'No order specified') unless @opts[:order]
447   reverse.first(*args, &block)
448 end
map(column=nil, &block) click to toggle source

Maps column values for each record in the dataset (if an argument is given) or performs the stock mapping functionality of Enumerable otherwise. Raises an Error if both an argument and block are given.

DB[:table].map(:id) # SELECT * FROM table
# => [1, 2, 3, ...]

DB[:table].map{|r| r[:id] * 2} # SELECT * FROM table
# => [2, 4, 6, ...]

You can also provide an array of column names:

DB[:table].map([:id, :name]) # SELECT * FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]
Calls superclass method
    # File lib/sequel/dataset/actions.rb
464 def map(column=nil, &block)
465   if column
466     raise(Error, 'Must call Dataset#map with either an argument or a block, not both') if block
467     return naked.map(column) if row_proc
468     if column.is_a?(Array)
469       super(){|r| r.values_at(*column)}
470     else
471       super(){|r| r[column]}
472     end
473   else
474     super(&block)
475   end
476 end
max(arg=(no_arg = true), &block) click to toggle source

Returns the maximum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].max(:id) # SELECT max(id) FROM table LIMIT 1
# => 10
DB[:table].max{function(column)} # SELECT max(function(column)) FROM table LIMIT 1
# => 7
    # File lib/sequel/dataset/actions.rb
485 def max(arg=(no_arg = true), &block)
486   arg = Sequel.virtual_row(&block) if no_arg
487   _aggregate(:max, arg)
488 end
merge() click to toggle source

Execute a MERGE statement, which allows for INSERT, UPDATE, and DELETE behavior in a single query, based on whether rows from a source table match rows in the current table, based on the join conditions.

Unless the dataset uses static SQL, to use merge, you must first have called merge_using to specify the merge source and join conditions. You will then likely to call one or more of the following methods to specify MERGE behavior by adding WHEN [NOT] MATCHED clauses:

The WHEN [NOT] MATCHED clauses are added to the SQL in the order these methods were called on the dataset. If none of these methods are called, an error is raised.

Example:

DB[:m1]
  merge_using(:m2, i1: :i2).
  merge_insert(i1: :i2, a: Sequel[:b]+11).
  merge_delete{a > 30}.
  merge_update(i1: Sequel[:i1]+:i2+10, a: Sequel[:a]+:b+20).
  merge

SQL:

MERGE INTO m1 USING m2 ON (i1 = i2)
WHEN NOT MATCHED THEN INSERT (i1, a) VALUES (i2, (b + 11))
WHEN MATCHED AND (a > 30) THEN DELETE
WHEN MATCHED THEN UPDATE SET i1 = (i1 + i2 + 10), a = (a + b + 20)

On PostgreSQL, two additional merge methods are supported, for the PostgreSQL-specific DO NOTHING syntax.

  • merge_do_nothing_when_matched

  • merge_do_nothing_when_not_matched

This method is supported on Oracle, but Oracle's MERGE support is non-standard, and has the following issues:

  • DELETE clause requires UPDATE clause

  • DELETE clause requires a condition

  • DELETE clause only affects rows updated by UPDATE clause

    # File lib/sequel/dataset/actions.rb
535 def merge
536   execute_ddl(merge_sql)
537 end
min(arg=(no_arg = true), &block) click to toggle source

Returns the minimum value for the given column/expression. Uses a virtual row block if no argument is given.

DB[:table].min(:id) # SELECT min(id) FROM table LIMIT 1
# => 1
DB[:table].min{function(column)} # SELECT min(function(column)) FROM table LIMIT 1
# => 0
    # File lib/sequel/dataset/actions.rb
546 def min(arg=(no_arg = true), &block)
547   arg = Sequel.virtual_row(&block) if no_arg
548   _aggregate(:min, arg)
549 end
multi_insert(hashes, opts=OPTS) click to toggle source

This is a front end for import that allows you to submit an array of hashes instead of arrays of columns and values:

DB[:table].multi_insert([{x: 1}, {x: 2}])
# INSERT INTO table (x) VALUES (1)
# INSERT INTO table (x) VALUES (2)

Be aware that all hashes should have the same keys if you use this calling method, otherwise some columns could be missed or set to null instead of to default values.

This respects the same options as import.

    # File lib/sequel/dataset/actions.rb
563 def multi_insert(hashes, opts=OPTS)
564   return if hashes.empty?
565   columns = hashes.first.keys
566   import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
567 end
paged_each(opts=OPTS) { || ... } click to toggle source

Yields each row in the dataset, but internally uses multiple queries as needed to process the entire result set without keeping all rows in the dataset in memory, even if the underlying driver buffers all query results in memory.

Because this uses multiple queries internally, in order to remain consistent, it also uses a transaction internally. Additionally, to work correctly, the dataset must have unambiguous order. Using an ambiguous order can result in an infinite loop, as well as subtler bugs such as yielding duplicate rows or rows being skipped.

Sequel checks that the datasets using this method have an order, but it cannot ensure that the order is unambiguous.

Note that this method is not safe to use on many adapters if you are running additional queries inside the provided block. If you are running queries inside the block, use a separate thread or shard inside paged_each.

Options:

:rows_per_fetch

The number of rows to fetch per query. Defaults to 1000.

:strategy

The strategy to use for paging of results. By default this is :offset, for using an approach with a limit and offset for every page. This can be set to :filter, which uses a limit and a filter that excludes rows from previous pages. In order for this strategy to work, you must be selecting the columns you are ordering by, and none of the columns can contain NULLs. Note that some Sequel adapters have optimized implementations that will use cursors or streaming regardless of the :strategy option used.

:filter_values

If the strategy: :filter option is used, this option should be a proc that accepts the last retrieved row for the previous page and an array of ORDER BY expressions, and returns an array of values relating to those expressions for the last retrieved row. You will need to use this option if your ORDER BY expressions are not simple columns, if they contain qualified identifiers that would be ambiguous unqualified, if they contain any identifiers that are aliased in SELECT, and potentially other cases.

:skip_transaction

Do not use a transaction. This can be useful if you want to prevent a lock on the database table, at the expense of consistency.

Examples:

DB[:table].order(:id).paged_each{|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table ORDER BY id LIMIT 1000 OFFSET 1000
# ...

DB[:table].order(:id).paged_each(rows_per_fetch: 100){|row| }
# SELECT * FROM table ORDER BY id LIMIT 100
# SELECT * FROM table ORDER BY id LIMIT 100 OFFSET 100
# ...

DB[:table].order(:id).paged_each(strategy: :filter){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...

DB[:table].order(:id).paged_each(strategy: :filter,
  filter_values: lambda{|row, exprs| [row[:id]]}){|row| }
# SELECT * FROM table ORDER BY id LIMIT 1000
# SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
# ...
    # File lib/sequel/dataset/actions.rb
626 def paged_each(opts=OPTS)
627   unless @opts[:order]
628     raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
629   end
630   unless defined?(yield)
631     return enum_for(:paged_each, opts)
632   end
633 
634   total_limit = @opts[:limit]
635   offset = @opts[:offset]
636   if server = @opts[:server]
637     opts = Hash[opts]
638     opts[:server] = server
639   end
640 
641   rows_per_fetch = opts[:rows_per_fetch] || 1000
642   strategy = if offset || total_limit
643     :offset
644   else
645     opts[:strategy] || :offset
646   end
647 
648   db.transaction(opts) do
649     case strategy
650     when :filter
651       filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
652       base_ds = ds = limit(rows_per_fetch)
653       while ds
654         last_row = nil
655         ds.each do |row|
656           last_row = row
657           yield row
658         end
659         ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
660       end
661     else
662       offset ||= 0
663       num_rows_yielded = rows_per_fetch
664       total_rows = 0
665 
666       while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
667         if total_limit && total_rows + rows_per_fetch > total_limit
668           rows_per_fetch = total_limit - total_rows
669         end
670 
671         num_rows_yielded = 0
672         limit(rows_per_fetch, offset).each do |row|
673           num_rows_yielded += 1
674           total_rows += 1 if total_limit
675           yield row
676         end
677 
678         offset += rows_per_fetch
679       end
680     end
681   end
682 
683   self
684 end
select_hash(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and value_column values as values. Similar to as_hash, but only selects the columns given. Like as_hash, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash(:id, :name)
# SELECT id, name FROM table
# => {1=>'a', 2=>'b', ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash([:id, :foo], [:name, :bar])
# SELECT id, foo, name, bar FROM table
# => {[1, 3]=>['a', 'c'], [2, 4]=>['b', 'd'], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
704 def select_hash(key_column, value_column, opts = OPTS)
705   _select_hash(:as_hash, key_column, value_column, opts)
706 end
select_hash_groups(key_column, value_column, opts = OPTS) click to toggle source

Returns a hash with key_column values as keys and an array of value_column values. Similar to to_hash_groups, but only selects the columns given. Like to_hash_groups, it accepts an optional :hash parameter, into which entries will be merged.

DB[:table].select_hash_groups(:name, :id)
# SELECT id, name FROM table
# => {'a'=>[1, 4, ...], 'b'=>[2, ...], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].select_hash_groups([:first, :middle], [:last, :id])
# SELECT first, middle, last, id FROM table
# => {['a', 'b']=>[['c', 1], ['d', 2], ...], ...}

When using this method, you must be sure that each expression has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
725 def select_hash_groups(key_column, value_column, opts = OPTS)
726   _select_hash(:to_hash_groups, key_column, value_column, opts)
727 end
select_map(column=nil, &block) click to toggle source

Selects the column given (either as an argument or as a block), and returns an array of all values of that column in the dataset. If you give a block argument that returns an array with multiple entries, the contents of the resulting array are undefined. Raises an Error if called with both an argument and a block.

DB[:table].select_map(:id) # SELECT id FROM table
# => [3, 5, 8, 1, ...]

DB[:table].select_map{id * 2} # SELECT (id * 2) FROM table
# => [6, 10, 16, 2, ...]

You can also provide an array of column names:

DB[:table].select_map([:id, :name]) # SELECT id, name FROM table
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
748 def select_map(column=nil, &block)
749   _select_map(column, false, &block)
750 end
select_order_map(column=nil, &block) click to toggle source

The same as select_map, but in addition orders the array by the column.

DB[:table].select_order_map(:id) # SELECT id FROM table ORDER BY id
# => [1, 2, 3, 4, ...]

DB[:table].select_order_map{id * 2} # SELECT (id * 2) FROM table ORDER BY (id * 2)
# => [2, 4, 6, 8, ...]

You can also provide an array of column names:

DB[:table].select_order_map([:id, :name]) # SELECT id, name FROM table ORDER BY id, name
# => [[1, 'A'], [2, 'B'], [3, 'C'], ...]

If you provide an array of expressions, you must be sure that each entry in the array has an alias that Sequel can determine.

    # File lib/sequel/dataset/actions.rb
767 def select_order_map(column=nil, &block)
768   _select_map(column, true, &block)
769 end
single_record() click to toggle source

Limits the dataset to one record, and returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method. Example:

DB[:test].single_record # SELECT * FROM test LIMIT 1
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
777 def single_record
778   _single_record_ds.single_record!
779 end
single_record!() click to toggle source

Returns the first record in dataset, without limiting the dataset. Returns nil if the dataset has no records. Users should probably use first instead of this method. This should only be used if you know the dataset is already limited to a single record. This method may be desirable to use for performance reasons, as it does not clone the receiver. Example:

DB[:test].single_record! # SELECT * FROM test
# => {:column_name=>'value'}
    # File lib/sequel/dataset/actions.rb
789 def single_record!
790   with_sql_first(select_sql)
791 end
single_value() click to toggle source

Returns the first value of the first record in the dataset. Returns nil if dataset is empty. Users should generally use get instead of this method. Example:

DB[:test].single_value # SELECT * FROM test LIMIT 1
# => 'value'
    # File lib/sequel/dataset/actions.rb
799 def single_value
800   single_value_ds.each do |r|
801     r.each{|_, v| return v}
802   end
803   nil
804 end
single_value!() click to toggle source

Returns the first value of the first record in the dataset, without limiting the dataset. Returns nil if the dataset is empty. Users should generally use get instead of this method. Should not be used on graphed datasets or datasets that have row_procs that don't return hashes. This method may be desirable to use for performance reasons, as it does not clone the receiver.

DB[:test].single_value! # SELECT * FROM test
# => 'value'
    # File lib/sequel/dataset/actions.rb
814 def single_value!
815   with_sql_single_value(select_sql)
816 end
sum(arg=(no_arg = true), &block) click to toggle source

Returns the sum for the given column/expression. Uses a virtual row block if no column is given.

DB[:table].sum(:id) # SELECT sum(id) FROM table LIMIT 1
# => 55
DB[:table].sum{function(column)} # SELECT sum(function(column)) FROM table LIMIT 1
# => 10
    # File lib/sequel/dataset/actions.rb
825 def sum(arg=(no_arg = true), &block)
826   arg = Sequel.virtual_row(&block) if no_arg
827   _aggregate(:sum, arg)
828 end
to_hash(*a) click to toggle source

Alias of as_hash for backwards compatibility.

    # File lib/sequel/dataset/actions.rb
882 def to_hash(*a)
883   as_hash(*a)
884 end
to_hash_groups(key_column, value_column = nil, opts = OPTS) click to toggle source

Returns a hash with one column used as key and the values being an array of column values. If the value_column is not given or nil, uses the entire hash as the value.

DB[:table].to_hash_groups(:name, :id) # SELECT * FROM table
# {'Jim'=>[1, 4, 16, ...], 'Bob'=>[2], ...}

DB[:table].to_hash_groups(:name) # SELECT * FROM table
# {'Jim'=>[{:id=>1, :name=>'Jim'}, {:id=>4, :name=>'Jim'}, ...], 'Bob'=>[{:id=>2, :name=>'Bob'}], ...}

You can also provide an array of column names for either the key_column, the value column, or both:

DB[:table].to_hash_groups([:first, :middle], [:last, :id]) # SELECT * FROM table
# {['Jim', 'Bob']=>[['Smith', 1], ['Jackson', 4], ...], ...}

DB[:table].to_hash_groups([:first, :middle]) # SELECT * FROM table
# {['Jim', 'Bob']=>[{:id=>1, :first=>'Jim', :middle=>'Bob', :last=>'Smith'}, ...], ...}

Options:

:all

Use all instead of each to retrieve the objects

:hash

The object into which the values will be placed. If this is not given, an empty hash is used. This can be used to use a hash with a default value or default proc.

    # File lib/sequel/dataset/actions.rb
910 def to_hash_groups(key_column, value_column = nil, opts = OPTS)
911   h = opts[:hash] || {}
912   meth = opts[:all] ? :all : :each
913   if value_column
914     return naked.to_hash_groups(key_column, value_column, opts) if row_proc
915     if value_column.is_a?(Array)
916       if key_column.is_a?(Array)
917         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
918       else
919         public_send(meth){|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
920       end
921     else
922       if key_column.is_a?(Array)
923         public_send(meth){|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
924       else
925         public_send(meth){|r| (h[r[key_column]] ||= []) << r[value_column]}
926       end
927     end
928   elsif key_column.is_a?(Array)
929     public_send(meth){|r| (h[key_column.map{|k| r[k]}] ||= []) << r}
930   else
931     public_send(meth){|r| (h[r[key_column]] ||= []) << r}
932   end
933   h
934 end
truncate() click to toggle source

Truncates the dataset. Returns nil.

DB[:table].truncate # TRUNCATE table
# => nil
    # File lib/sequel/dataset/actions.rb
940 def truncate
941   execute_ddl(truncate_sql)
942 end
update(values=OPTS, &block) click to toggle source

Updates values for the dataset. The returned value is the number of rows updated. values should be a hash where the keys are columns to set and values are the values to which to set the columns.

DB[:table].update(x: nil) # UPDATE table SET x = NULL
# => 10

DB[:table].update(x: Sequel[:x]+1, y: 0) # UPDATE table SET x = (x + 1), y = 0
# => 10

Some databases support using multiple tables in an UPDATE query. This requires multiple FROM tables (JOINs can also be used). As multiple FROM tables use an implicit CROSS JOIN, you should make sure your WHERE condition uses the appropriate filters for the FROM tables:

DB.from(:a, :b).join(:c, :d=>Sequel[:b][:e]).where{{a[:f]=>b[:g], a[:id]=>10}}.
  update(:f=>Sequel[:c][:h])
# UPDATE a
# SET f = c.h
# FROM b
# INNER JOIN c ON (c.d = b.e)
# WHERE ((a.f = b.g) AND (a.id = 10))
    # File lib/sequel/dataset/actions.rb
966 def update(values=OPTS, &block)
967   sql = update_sql(values)
968   if uses_returning?(:update)
969     returning_fetch_rows(sql, &block)
970   else
971     execute_dui(sql)
972   end
973 end
where_all(cond, &block) click to toggle source

Return an array of all rows matching the given filter condition, also yielding each row to the given block. Basically the same as where(cond).all(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_all(id: [1,2,3])
# SELECT * FROM table WHERE (id IN (1, 2, 3))
    # File lib/sequel/dataset/actions.rb
981 def where_all(cond, &block)
982   if loader = _where_loader([cond], nil)
983     loader.all(filter_expr(cond), &block)
984   else
985     where(cond).all(&block)
986   end
987 end
where_each(cond, &block) click to toggle source

Iterate over all rows matching the given filter condition, yielding each row to the given block. Basically the same as where(cond).each(&block), except it can be optimized to not create an intermediate dataset.

DB[:table].where_each(id: [1,2,3]){|row| p row}
# SELECT * FROM table WHERE (id IN (1, 2, 3))
     # File lib/sequel/dataset/actions.rb
 995 def where_each(cond, &block)
 996   if loader = _where_loader([cond], nil)
 997     loader.each(filter_expr(cond), &block)
 998   else
 999     where(cond).each(&block)
1000   end
1001 end
where_single_value(cond) click to toggle source

Filter the datasets using the given filter condition, then return a single value. This assumes that the dataset has already been setup to limit the selection to a single column. Basically the same as where(cond).single_value, except it can be optimized to not create an intermediate dataset.

DB[:table].select(:name).where_single_value(id: 1)
# SELECT name FROM table WHERE (id = 1) LIMIT 1
     # File lib/sequel/dataset/actions.rb
1010 def where_single_value(cond)
1011   if loader = cached_where_placeholder_literalizer([cond], nil, :_where_single_value_loader) do |pl|
1012       single_value_ds.where(pl.arg)
1013     end
1014 
1015     loader.get(filter_expr(cond))
1016   else
1017     where(cond).single_value
1018   end
1019 end
with_sql_all(sql, &block) click to toggle source

Run the given SQL and return an array of all rows. If a block is given, each row is yielded to the block after all rows are loaded. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1023 def with_sql_all(sql, &block)
1024   _all(block){|a| with_sql_each(sql){|r| a << r}}
1025 end
with_sql_delete(sql) click to toggle source

Execute the given SQL and return the number of rows deleted. This exists solely as an optimization, replacing with_sql(sql).delete. It's significantly faster as it does not require cloning the current dataset.

     # File lib/sequel/dataset/actions.rb
1030 def with_sql_delete(sql)
1031   execute_dui(sql)
1032 end
Also aliased as: with_sql_update
with_sql_each(sql) { |call| ... } click to toggle source

Run the given SQL and yield each returned row to the block.

     # File lib/sequel/dataset/actions.rb
1036 def with_sql_each(sql)
1037   if rp = row_proc
1038     _with_sql_dataset.fetch_rows(sql){|r| yield rp.call(r)}
1039   else
1040     _with_sql_dataset.fetch_rows(sql){|r| yield r}
1041   end
1042   self
1043 end
with_sql_first(sql) click to toggle source

Run the given SQL and return the first row, or nil if no rows were returned. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1047 def with_sql_first(sql)
1048   with_sql_each(sql){|r| return r}
1049   nil
1050 end
with_sql_insert(sql) click to toggle source

Execute the given SQL and (on most databases) return the primary key of the inserted row.

     # File lib/sequel/dataset/actions.rb
1063 def with_sql_insert(sql)
1064   execute_insert(sql)
1065 end
with_sql_single_value(sql) click to toggle source

Run the given SQL and return the first value in the first row, or nil if no rows were returned. For this to make sense, the SQL given should select only a single value. See with_sql_each.

     # File lib/sequel/dataset/actions.rb
1055 def with_sql_single_value(sql)
1056   if r = with_sql_first(sql)
1057     r.each{|_, v| return v}
1058   end
1059 end
with_sql_update(sql)
Alias for: with_sql_delete

Protected Instance Methods

_import(columns, values, opts) click to toggle source

Internals of import. If primary key values are requested, use separate insert commands for each row. Otherwise, call multi_insert_sql and execute each statement it gives separately. A transaction is only used if there are multiple statements to execute.

     # File lib/sequel/dataset/actions.rb
1073 def _import(columns, values, opts)
1074   trans_opts = Hash[opts]
1075   trans_opts[:server] = @opts[:server]
1076   if opts[:return] == :primary_key
1077     _import_transaction(values, trans_opts){values.map{|v| insert(columns, v)}}
1078   else
1079     stmts = multi_insert_sql(columns, values)
1080     _import_transaction(stmts, trans_opts){stmts.each{|st| execute_dui(st)}}
1081   end
1082 end
_select_map_multiple(ret_cols) click to toggle source

Return an array of arrays of values given by the symbols in ret_cols.

     # File lib/sequel/dataset/actions.rb
1085 def _select_map_multiple(ret_cols)
1086   map{|r| r.values_at(*ret_cols)}
1087 end
_select_map_single() click to toggle source

Returns an array of the first value in each row.

     # File lib/sequel/dataset/actions.rb
1090 def _select_map_single
1091   k = nil
1092   map{|r| r[k||=r.keys.first]}
1093 end
single_value_ds() click to toggle source

A dataset for returning single values from the current dataset.

     # File lib/sequel/dataset/actions.rb
1096 def single_value_ds
1097   clone(:limit=>1).ungraphed.naked
1098 end

Private Instance Methods

_aggregate(function, arg) click to toggle source

Cached placeholder literalizer for methods that return values using aggregate functions.

     # File lib/sequel/dataset/actions.rb
1112 def _aggregate(function, arg)
1113   if loader = cached_placeholder_literalizer(:"_#{function}_loader") do |pl|
1114         aggregate_dataset.limit(1).select(SQL::Function.new(function, pl.arg).as(function))
1115       end
1116     loader.get(arg)
1117   else
1118     aggregate_dataset.get(SQL::Function.new(function, arg).as(function))
1119   end
1120 end
_all(block) { |a| ... } click to toggle source

Internals of all and with_sql_all

     # File lib/sequel/dataset/actions.rb
1103 def _all(block)
1104   a = []
1105   yield a
1106   post_load(a)
1107   a.each(&block) if block
1108   a
1109 end
_hash_key_symbol(s, recursing=false) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Return nil if no hash key can be determined

     # File lib/sequel/dataset/actions.rb
1220 def _hash_key_symbol(s, recursing=false)
1221   case s
1222   when Symbol
1223     _, c, a = split_symbol(s)
1224     (a || c).to_sym
1225   when SQL::Identifier, SQL::Wrapper
1226     _hash_key_symbol(s.value, true)
1227   when SQL::QualifiedIdentifier
1228     _hash_key_symbol(s.column, true)
1229   when SQL::AliasedExpression
1230     _hash_key_symbol(s.alias, true)
1231   when String
1232     s.to_sym if recursing
1233   end
1234 end
_import_transaction(values, trans_opts, &block) click to toggle source

Use a transaction when yielding to the block if multiple values/statements are provided. When only a single value or statement is provided, then yield without using a transaction.

     # File lib/sequel/dataset/actions.rb
1125 def _import_transaction(values, trans_opts, &block)
1126   # OK to mutate trans_opts as it is generated by _import
1127   trans_opts[:skip_transaction] = true if values.length <= 1
1128   @db.transaction(trans_opts, &block)
1129 end
_select_hash(meth, key_column, value_column, opts=OPTS) click to toggle source

Internals of select_hash and select_hash_groups

     # File lib/sequel/dataset/actions.rb
1132 def _select_hash(meth, key_column, value_column, opts=OPTS)
1133   select(*(key_column.is_a?(Array) ? key_column : [key_column]) + (value_column.is_a?(Array) ? value_column : [value_column])).
1134     public_send(meth, hash_key_symbols(key_column), hash_key_symbols(value_column), opts)
1135 end
_select_map(column, order, &block) click to toggle source

Internals of select_map and select_order_map

     # File lib/sequel/dataset/actions.rb
1138 def _select_map(column, order, &block)
1139   ds = ungraphed.naked
1140   columns = Array(column)
1141   virtual_row_columns(columns, block)
1142   select_cols = order ? columns.map{|c| c.is_a?(SQL::OrderedExpression) ? c.expression : c} : columns
1143   ds = ds.order(*columns.map{|c| unaliased_identifier(c)}) if order
1144   if column.is_a?(Array) || (columns.length > 1)
1145     ds.select(*select_cols)._select_map_multiple(hash_key_symbols(select_cols))
1146   else
1147     ds.select(auto_alias_expression(select_cols.first))._select_map_single
1148   end
1149 end
_single_record_ds() click to toggle source

A cached dataset for a single record for this dataset.

     # File lib/sequel/dataset/actions.rb
1152 def _single_record_ds
1153   cached_dataset(:_single_record_ds){clone(:limit=>1)}
1154 end
_where_loader(where_args, where_block) click to toggle source

Loader used for where_all and where_each.

     # File lib/sequel/dataset/actions.rb
1157 def _where_loader(where_args, where_block)
1158   cached_where_placeholder_literalizer(where_args, where_block, :_where_loader) do |pl|
1159     where(pl.arg)
1160   end
1161 end
_with_sql_dataset() click to toggle source

Cached dataset to use for with_sql_#{all,each,first,single_value}. This is used so that the columns returned by the given SQL do not affect the receiver of the with_sql_* method.

     # File lib/sequel/dataset/actions.rb
1338 def _with_sql_dataset
1339   if @opts[:_with_sql_ds]
1340     self
1341   else
1342     cached_dataset(:_with_sql_ds) do
1343       clone(:_with_sql_ds=>true)
1344     end
1345   end
1346 end
auto_alias_expression(v) click to toggle source

Automatically alias the given expression if it does not have an identifiable alias.

     # File lib/sequel/dataset/actions.rb
1164 def auto_alias_expression(v)
1165   case v
1166   when LiteralString, Symbol, SQL::Identifier, SQL::QualifiedIdentifier, SQL::AliasedExpression
1167     v
1168   else
1169     SQL::AliasedExpression.new(v, :v)
1170   end
1171 end
default_import_slice() click to toggle source

The default number of rows that can be inserted in a single INSERT statement via import. The default is for no limit.

     # File lib/sequel/dataset/actions.rb
1175 def default_import_slice
1176   nil
1177 end
default_server_opts(opts) click to toggle source

Set the server to use to :default unless it is already set in the passed opts

     # File lib/sequel/dataset/actions.rb
1180 def default_server_opts(opts)
1181   if @db.sharded? && !opts.has_key?(:server)
1182     opts = Hash[opts]
1183     opts[:server] = @opts[:server] || :default
1184   end
1185   opts
1186 end
execute(sql, opts=OPTS, &block) click to toggle source

Execute the given select SQL on the database using execute. Use the :read_only server unless a specific server is set.

     # File lib/sequel/dataset/actions.rb
1190 def execute(sql, opts=OPTS, &block)
1191   db = @db
1192   if db.sharded? && !opts.has_key?(:server)
1193     opts = Hash[opts]
1194     opts[:server] = @opts[:server] || (@opts[:lock] ? :default : :read_only)
1195     opts
1196   end
1197   db.execute(sql, opts, &block)
1198 end
execute_ddl(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_ddl.

     # File lib/sequel/dataset/actions.rb
1201 def execute_ddl(sql, opts=OPTS, &block)
1202   @db.execute_ddl(sql, default_server_opts(opts), &block)
1203   nil
1204 end
execute_dui(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_dui.

     # File lib/sequel/dataset/actions.rb
1207 def execute_dui(sql, opts=OPTS, &block)
1208   @db.execute_dui(sql, default_server_opts(opts), &block)
1209 end
execute_insert(sql, opts=OPTS, &block) click to toggle source

Execute the given SQL on the database using execute_insert.

     # File lib/sequel/dataset/actions.rb
1212 def execute_insert(sql, opts=OPTS, &block)
1213   @db.execute_insert(sql, default_server_opts(opts), &block)
1214 end
hash_key_symbol(s) click to toggle source

Return a plain symbol given a potentially qualified or aliased symbol, specifying the symbol that is likely to be used as the hash key for the column when records are returned. Raise Error if the hash key symbol cannot be returned.

     # File lib/sequel/dataset/actions.rb
1240 def hash_key_symbol(s)
1241   if v = _hash_key_symbol(s)
1242     v
1243   else
1244     raise(Error, "#{s.inspect} is not supported, should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression")
1245   end
1246 end
hash_key_symbols(s) click to toggle source

If s is an array, return an array with the given hash key symbols. Otherwise, return a hash key symbol for the given expression If a hash key symbol cannot be determined, raise an error.

     # File lib/sequel/dataset/actions.rb
1251 def hash_key_symbols(s)
1252   s.is_a?(Array) ? s.map{|c| hash_key_symbol(c)} : hash_key_symbol(s)
1253 end
ignore_values_preceding(row) { |row, map(&:first)| ... } click to toggle source

Returns an expression that will ignore values preceding the given row, using the receiver's current order. This yields the row and the array of order expressions to the block, which should return an array of values to use.

     # File lib/sequel/dataset/actions.rb
1258 def ignore_values_preceding(row)
1259   @opts[:order].map{|v| v.is_a?(SQL::OrderedExpression) ? v.expression : v}
1260 
1261   order_exprs = @opts[:order].map do |v|
1262     if v.is_a?(SQL::OrderedExpression)
1263       descending = v.descending
1264       v = v.expression
1265     else
1266       descending = false
1267     end
1268     [v, descending]
1269   end
1270 
1271   row_values = yield(row, order_exprs.map(&:first))
1272 
1273   last_expr = []
1274   cond = order_exprs.zip(row_values).map do |(v, descending), value|
1275     expr =  last_expr + [SQL::BooleanExpression.new(descending ? :< : :>, v, value)]
1276     last_expr += [SQL::BooleanExpression.new(:'=', v, value)]
1277     Sequel.&(*expr)
1278   end
1279   Sequel.|(*cond)
1280 end
output_identifier(v) click to toggle source

Downcase identifiers by default when outputing them from the database.

     # File lib/sequel/dataset/actions.rb
1283 def output_identifier(v)
1284   v = 'untitled' if v == ''
1285   v.to_s.downcase.to_sym
1286 end
post_load(all_records) click to toggle source

This is run inside .all, after all of the records have been loaded via .each, but before any block passed to all is called. It is called with a single argument, an array of all returned records. Does nothing by default, added to make the model eager loading code simpler.

     # File lib/sequel/dataset/actions.rb
1292 def post_load(all_records)
1293 end
returning_fetch_rows(sql, &block) click to toggle source

Called by insert/update/delete when returning is used. Yields each row as a plain hash to the block if one is given, or returns an array of plain hashes for all rows if a block is not given

     # File lib/sequel/dataset/actions.rb
1298 def returning_fetch_rows(sql, &block)
1299   if block
1300     default_server.fetch_rows(sql, &block)
1301     nil
1302   else
1303     rows = []
1304     default_server.fetch_rows(sql){|r| rows << r}
1305     rows
1306   end
1307 end
unaliased_identifier(c) click to toggle source

Return the unaliased part of the identifier. Handles both implicit aliases in symbols, as well as SQL::AliasedExpression objects. Other objects are returned as is.

     # File lib/sequel/dataset/actions.rb
1312 def unaliased_identifier(c)
1313   case c
1314   when Symbol
1315     table, column, aliaz = split_symbol(c)
1316     if aliaz
1317       table ? SQL::QualifiedIdentifier.new(table, column) : Sequel.identifier(column)
1318     else
1319       c
1320     end
1321   when SQL::AliasedExpression
1322     c.expression
1323   when SQL::OrderedExpression
1324     case expr = c.expression
1325     when Symbol, SQL::AliasedExpression
1326       SQL::OrderedExpression.new(unaliased_identifier(expr), c.descending, :nulls=>c.nulls)
1327     else
1328       c
1329     end
1330   else
1331     c
1332   end
1333 end

3 - User Methods relating to SQL Creation

↑ top

Public Instance Methods

exists() click to toggle source

Returns an EXISTS clause for the dataset as an SQL::PlaceholderLiteralString.

DB.select(1).where(DB[:items].exists)
# SELECT 1 WHERE (EXISTS (SELECT * FROM items))
   # File lib/sequel/dataset/sql.rb
14 def exists
15   SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
16 end
insert_sql(*values) click to toggle source

Returns an INSERT SQL query string. See insert.

DB[:items].insert_sql(a: 1)
# => "INSERT INTO items (a) VALUES (1)"
   # File lib/sequel/dataset/sql.rb
22 def insert_sql(*values)
23   return static_sql(@opts[:sql]) if @opts[:sql]
24 
25   check_insert_allowed!
26 
27   columns, values = _parse_insert_sql_args(values)
28   if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
29     columns, values = insert_empty_columns_values
30   elsif values.is_a?(Dataset) && hoist_cte?(values) && supports_cte?(:insert)
31     ds, values = hoist_cte(values)
32     return ds.clone(:columns=>columns, :values=>values).send(:_insert_sql)
33   end
34   clone(:columns=>columns, :values=>values).send(:_insert_sql)
35 end
literal_append(sql, v) click to toggle source

Append a literal representation of a value to the given SQL string.

If an unsupported object is given, an Error is raised.

   # File lib/sequel/dataset/sql.rb
40 def literal_append(sql, v)
41   case v
42   when Symbol
43     if skip_symbol_cache?
44       literal_symbol_append(sql, v)
45     else 
46       unless l = db.literal_symbol(v)
47         l = String.new
48         literal_symbol_append(l, v)
49         db.literal_symbol_set(v, l)
50       end
51       sql << l
52     end
53   when String
54     case v
55     when LiteralString
56       sql << v
57     when SQL::Blob
58       literal_blob_append(sql, v)
59     else
60       literal_string_append(sql, v)
61     end
62   when Integer
63     sql << literal_integer(v)
64   when Hash
65     literal_hash_append(sql, v)
66   when SQL::Expression
67     literal_expression_append(sql, v)
68   when Float
69     sql << literal_float(v)
70   when BigDecimal
71     sql << literal_big_decimal(v)
72   when NilClass
73     sql << literal_nil
74   when TrueClass
75     sql << literal_true
76   when FalseClass
77     sql << literal_false
78   when Array
79     literal_array_append(sql, v)
80   when Time
81     v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v)
82   when DateTime
83     literal_datetime_append(sql, v)
84   when Date
85     literal_date_append(sql, v)
86   when Dataset
87     literal_dataset_append(sql, v)
88   else
89     literal_other_append(sql, v)
90   end
91 end
literal_date_or_time(dt, raw=false) click to toggle source

Literalize a date or time value, as a SQL string value with no typecasting. If raw is true, remove the surrounding single quotes. This is designed for usage by bound argument code that can work even if the auto_cast_date_and_time extension is used (either manually or implicitly in the related adapter).

    # File lib/sequel/dataset/sql.rb
123 def literal_date_or_time(dt, raw=false)
124   value = case dt
125   when SQLTime
126     literal_sqltime(dt)
127   when Time
128     literal_time(dt)
129   when DateTime
130     literal_datetime(dt)
131   when Date
132     literal_date(dt)
133   else
134     raise TypeError, "unsupported type: #{dt.inspect}"
135   end
136 
137   if raw
138     value.sub!(/\A'/, '')
139     value.sub!(/'\z/, '')
140   end
141 
142   value
143 end
merge_sql() click to toggle source

The SQL to use for the MERGE statement.

    # File lib/sequel/dataset/sql.rb
 94 def merge_sql
 95   raise Error, "This database doesn't support MERGE" unless supports_merge?
 96   if sql = opts[:sql]
 97     return static_sql(sql)
 98   end
 99   if sql = cache_get(:_merge_sql)
100     return sql
101   end
102   source, join_condition = @opts[:merge_using]
103   raise Error, "No USING clause for MERGE" unless source
104   sql = @opts[:append_sql] || sql_string_origin
105 
106   select_with_sql(sql)
107   sql << "MERGE INTO "
108   source_list_append(sql, @opts[:from])
109   sql << " USING "
110   identifier_append(sql, source)
111   sql << " ON "
112   literal_append(sql, join_condition)
113   _merge_when_sql(sql)
114   cache_set(:_merge_sql, sql) if cache_sql?
115   sql
116 end
multi_insert_sql(columns, values) click to toggle source

Returns an array of insert statements for inserting multiple records. This method is used by multi_insert to format insert statements and expects a keys array and and an array of value arrays.

    # File lib/sequel/dataset/sql.rb
148 def multi_insert_sql(columns, values)
149   case multi_insert_sql_strategy
150   when :values
151     sql = LiteralString.new('VALUES ')
152     expression_list_append(sql, values.map{|r| Array(r)})
153     [insert_sql(columns, sql)]
154   when :union
155     c = false
156     sql = LiteralString.new
157     u = ' UNION ALL SELECT '
158     f = empty_from_sql
159     values.each do |v|
160       if c
161         sql << u
162       else
163         sql << 'SELECT '
164         c = true
165       end
166       expression_list_append(sql, v)
167       sql << f if f
168     end
169     [insert_sql(columns, sql)]
170   else
171     values.map{|r| insert_sql(columns, r)}
172   end
173 end
sql() click to toggle source

Same as select_sql, not aliased directly to make subclassing simpler.

    # File lib/sequel/dataset/sql.rb
176 def sql
177   select_sql
178 end
truncate_sql() click to toggle source

Returns a TRUNCATE SQL query string. See truncate

DB[:items].truncate_sql # => 'TRUNCATE items'
    # File lib/sequel/dataset/sql.rb
183 def truncate_sql
184   if opts[:sql]
185     static_sql(opts[:sql])
186   else
187     check_truncation_allowed!
188     check_not_limited!(:truncate)
189     raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
190     t = String.new
191     source_list_append(t, opts[:from])
192     _truncate_sql(t)
193   end
194 end
update_sql(values = OPTS) click to toggle source

Formats an UPDATE statement using the given values. See update.

DB[:items].update_sql(price: 100, category: 'software')
# => "UPDATE items SET price = 100, category = 'software'

Raises an Error if the dataset is grouped or includes more than one table.

    # File lib/sequel/dataset/sql.rb
203 def update_sql(values = OPTS)
204   return static_sql(opts[:sql]) if opts[:sql]
205   check_update_allowed!
206   check_not_limited!(:update)
207 
208   case values
209   when LiteralString
210     # nothing
211   when String
212     raise Error, "plain string passed to Dataset#update is not supported, use Sequel.lit to use a literal string"
213   end
214 
215   clone(:values=>values).send(:_update_sql)
216 end

4 - Methods that describe what the dataset supports

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Public Instance Methods

provides_accurate_rows_matched?() click to toggle source

Whether this dataset will provide accurate number of rows matched for delete and update statements, true by default. Accurate in this case is the number of rows matched by the dataset's filter.

   # File lib/sequel/dataset/features.rb
19 def provides_accurate_rows_matched?
20   true
21 end
quote_identifiers?() click to toggle source

Whether this dataset quotes identifiers.

   # File lib/sequel/dataset/features.rb
12 def quote_identifiers?
13   @opts.fetch(:quote_identifiers, true)
14 end
recursive_cte_requires_column_aliases?() click to toggle source

Whether you must use a column alias list for recursive CTEs, false by default.

   # File lib/sequel/dataset/features.rb
24 def recursive_cte_requires_column_aliases?
25   false
26 end
requires_placeholder_type_specifiers?() click to toggle source

Whether type specifiers are required for prepared statement/bound variable argument placeholders (i.e. :bv__integer), false by default.

   # File lib/sequel/dataset/features.rb
41 def requires_placeholder_type_specifiers?
42   false
43 end
requires_sql_standard_datetimes?() click to toggle source

Whether the dataset requires SQL standard datetimes. False by default, as most allow strings with ISO 8601 format. Only for backwards compatibility, no longer used internally, do not use in new code.

   # File lib/sequel/dataset/features.rb
33 def requires_sql_standard_datetimes?
34   # SEQUEL6: Remove
35   false
36 end
supports_cte?(type=:select) click to toggle source

Whether the dataset supports common table expressions, false by default. If given, type can be :select, :insert, :update, or :delete, in which case it determines whether WITH is supported for the respective statement type.

   # File lib/sequel/dataset/features.rb
48 def supports_cte?(type=:select)
49   false
50 end
supports_cte_in_subqueries?() click to toggle source

Whether the dataset supports common table expressions in subqueries, false by default. If false, applies the WITH clause to the main query, which can cause issues if multiple WITH clauses use the same name.

   # File lib/sequel/dataset/features.rb
55 def supports_cte_in_subqueries?
56   false
57 end
supports_deleting_joins?() click to toggle source

Whether deleting from joined datasets is supported, false by default.

   # File lib/sequel/dataset/features.rb
60 def supports_deleting_joins?
61   supports_modifying_joins?
62 end
supports_derived_column_lists?() click to toggle source

Whether the database supports derived column lists (e.g. “table_expr AS table_alias(column_alias1, column_alias2, …)”), true by default.

   # File lib/sequel/dataset/features.rb
67 def supports_derived_column_lists?
68   true
69 end
supports_distinct_on?() click to toggle source

Whether the dataset supports or can emulate the DISTINCT ON clause, false by default.

   # File lib/sequel/dataset/features.rb
72 def supports_distinct_on?
73   false
74 end
supports_group_cube?() click to toggle source

Whether the dataset supports CUBE with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
77 def supports_group_cube?
78   false
79 end
supports_group_rollup?() click to toggle source

Whether the dataset supports ROLLUP with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
82 def supports_group_rollup?
83   false
84 end
supports_grouping_sets?() click to toggle source

Whether the dataset supports GROUPING SETS with GROUP BY, false by default.

   # File lib/sequel/dataset/features.rb
87 def supports_grouping_sets?
88   false
89 end
supports_insert_select?() click to toggle source

Whether this dataset supports the insert_select method for returning all columns values directly from an insert query, false by default.

   # File lib/sequel/dataset/features.rb
93 def supports_insert_select?
94   supports_returning?(:insert)
95 end
supports_intersect_except?() click to toggle source

Whether the dataset supports the INTERSECT and EXCEPT compound operations, true by default.

    # File lib/sequel/dataset/features.rb
 98 def supports_intersect_except?
 99   true
100 end
supports_intersect_except_all?() click to toggle source

Whether the dataset supports the INTERSECT ALL and EXCEPT ALL compound operations, true by default.

    # File lib/sequel/dataset/features.rb
103 def supports_intersect_except_all?
104   true
105 end
supports_is_true?() click to toggle source

Whether the dataset supports the IS TRUE syntax, true by default.

    # File lib/sequel/dataset/features.rb
108 def supports_is_true?
109   true
110 end
supports_join_using?() click to toggle source

Whether the dataset supports the JOIN table USING (column1, …) syntax, true by default. If false, support is emulated using JOIN table ON (table.column1 = other_table.column1).

    # File lib/sequel/dataset/features.rb
114 def supports_join_using?
115   true
116 end
supports_lateral_subqueries?() click to toggle source

Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses, false by default.

    # File lib/sequel/dataset/features.rb
119 def supports_lateral_subqueries?
120   false
121 end
supports_limits_in_correlated_subqueries?() click to toggle source

Whether limits are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
124 def supports_limits_in_correlated_subqueries?
125   true
126 end
supports_merge?() click to toggle source

Whether the MERGE statement is supported, false by default.

    # File lib/sequel/dataset/features.rb
134 def supports_merge?
135   false
136 end
supports_modifying_joins?() click to toggle source

Whether modifying joined datasets is supported, false by default.

    # File lib/sequel/dataset/features.rb
139 def supports_modifying_joins?
140   false
141 end
supports_multiple_column_in?() click to toggle source

Whether the IN/NOT IN operators support multiple columns when an array of values is given, true by default.

    # File lib/sequel/dataset/features.rb
145 def supports_multiple_column_in?
146   true
147 end
supports_nowait?() click to toggle source

Whether the dataset supports skipping raising an error instead of waiting for locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
129 def supports_nowait?
130   false
131 end
supports_offsets_in_correlated_subqueries?() click to toggle source

Whether offsets are supported in correlated subqueries, true by default.

    # File lib/sequel/dataset/features.rb
150 def supports_offsets_in_correlated_subqueries?
151   true
152 end
supports_ordered_distinct_on?() click to toggle source

Whether the dataset supports or can fully emulate the DISTINCT ON clause, including respecting the ORDER BY clause, false by default.

    # File lib/sequel/dataset/features.rb
156 def supports_ordered_distinct_on?
157   supports_distinct_on?
158 end
supports_placeholder_literalizer?() click to toggle source

Whether placeholder literalizers are supported, true by default.

    # File lib/sequel/dataset/features.rb
161 def supports_placeholder_literalizer?
162   true
163 end
supports_regexp?() click to toggle source

Whether the dataset supports pattern matching by regular expressions, false by default.

    # File lib/sequel/dataset/features.rb
166 def supports_regexp?
167   false
168 end
supports_replace?() click to toggle source

Whether the dataset supports REPLACE syntax, false by default.

    # File lib/sequel/dataset/features.rb
171 def supports_replace?
172   false
173 end
supports_returning?(type) click to toggle source

Whether the RETURNING clause is supported for the given type of query, false by default. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
177 def supports_returning?(type)
178   false
179 end
supports_select_all_and_column?() click to toggle source

Whether the database supports SELECT *, column FROM table, true by default.

    # File lib/sequel/dataset/features.rb
187 def supports_select_all_and_column?
188   true
189 end
supports_skip_locked?() click to toggle source

Whether the dataset supports skipping locked rows when returning data, false by default.

    # File lib/sequel/dataset/features.rb
182 def supports_skip_locked?
183   false
184 end
supports_timestamp_timezones?() click to toggle source

Whether the dataset supports timezones in literal timestamps, false by default.

    # File lib/sequel/dataset/features.rb
194 def supports_timestamp_timezones?
195   # SEQUEL6: Remove
196   false
197 end
supports_timestamp_usecs?() click to toggle source

Whether the dataset supports fractional seconds in literal timestamps, true by default.

    # File lib/sequel/dataset/features.rb
201 def supports_timestamp_usecs?
202   true
203 end
supports_updating_joins?() click to toggle source

Whether updating joined datasets is supported, false by default.

    # File lib/sequel/dataset/features.rb
206 def supports_updating_joins?
207   supports_modifying_joins?
208 end
supports_where_true?() click to toggle source

Whether the dataset supports WHERE TRUE (or WHERE 1 for databases that that use 1 for true), true by default.

    # File lib/sequel/dataset/features.rb
235 def supports_where_true?
236   true
237 end
supports_window_clause?() click to toggle source

Whether the dataset supports the WINDOW clause to define windows used by multiple window functions, false by default.

    # File lib/sequel/dataset/features.rb
212 def supports_window_clause?
213   false
214 end
supports_window_function_frame_option?(option) click to toggle source

Whether the dataset supports the given window function option. True by default. This should only be called if supports_window_functions? is true. Possible options are :rows, :range, :groups, :offset, :exclude.

    # File lib/sequel/dataset/features.rb
224 def supports_window_function_frame_option?(option)
225   case option
226   when :rows, :range, :offset
227     true
228   else
229     false
230   end
231 end
supports_window_functions?() click to toggle source

Whether the dataset supports window functions, false by default.

    # File lib/sequel/dataset/features.rb
217 def supports_window_functions?
218   false
219 end

Private Instance Methods

insert_supports_empty_values?() click to toggle source

Whether insert(nil) or insert({}) must be emulated by using at least one value.

    # File lib/sequel/dataset/features.rb
243 def insert_supports_empty_values?
244   true
245 end
requires_emulating_nulls_first?() click to toggle source

Whether ORDER BY col NULLS FIRST/LAST must be emulated.

    # File lib/sequel/dataset/features.rb
253 def requires_emulating_nulls_first?
254   false
255 end
requires_like_escape?() click to toggle source

Whether the dataset needs ESCAPE for LIKE for correct behavior.

    # File lib/sequel/dataset/features.rb
248 def requires_like_escape?
249   true
250 end
supports_cte_in_compounds?() click to toggle source

Whether common table expressions are supported in UNION/INTERSECT/EXCEPT clauses.

    # File lib/sequel/dataset/features.rb
258 def supports_cte_in_compounds?
259   supports_cte_in_subqueries?
260 end
supports_filtered_aggregates?() click to toggle source

Whether the dataset supports the FILTER clause for aggregate functions. If not, support is emulated using CASE.

    # File lib/sequel/dataset/features.rb
264 def supports_filtered_aggregates?
265   false
266 end
supports_quoted_function_names?() click to toggle source

Whether the database supports quoting function names.

    # File lib/sequel/dataset/features.rb
269 def supports_quoted_function_names?
270   false
271 end
uses_returning?(type) click to toggle source

Whether the RETURNING clause is used for the given dataset. type can be :insert, :update, or :delete.

    # File lib/sequel/dataset/features.rb
275 def uses_returning?(type)
276   opts[:returning] && !@opts[:sql] && supports_returning?(type)
277 end
uses_with_rollup?() click to toggle source

Whether the dataset uses WITH ROLLUP/CUBE instead of ROLLUP()/CUBE().

    # File lib/sequel/dataset/features.rb
280 def uses_with_rollup?
281   false
282 end

5 - Methods related to dataset graphing

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Public Instance Methods

add_graph_aliases(graph_aliases) click to toggle source

Adds the given graph aliases to the list of graph aliases to use, unlike set_graph_aliases, which replaces the list (the equivalent of select_append when graphing). See set_graph_aliases.

DB[:table].add_graph_aliases(some_alias: [:table, :column])
# SELECT ..., table.column AS some_alias
   # File lib/sequel/dataset/graph.rb
18 def add_graph_aliases(graph_aliases)
19   graph = opts[:graph]
20   unless (graph && (ga = graph[:column_aliases]))
21     raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases"
22   end
23   columns, graph_aliases = graph_alias_columns(graph_aliases)
24   select_append(*columns).clone(:graph => graph.merge(:column_aliases=>ga.merge(graph_aliases).freeze).freeze)
25 end
graph(dataset, join_conditions = nil, options = OPTS, &block) click to toggle source

Similar to Dataset#join_table, but uses unambiguous aliases for selected columns and keeps metadata about the aliases for use in other methods.

Arguments:

dataset

Can be a symbol (specifying a table), another dataset, or an SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

join_conditions

Any condition(s) allowed by join_table.

block

A block that is passed to join_table.

Options:

:from_self_alias

The alias to use when the receiver is not a graphed dataset but it contains multiple FROM tables or a JOIN. In this case, the receiver is wrapped in a from_self before graphing, and this option determines the alias to use.

:implicit_qualifier

The qualifier of implicit conditions, see join_table.

:join_only

Only join the tables, do not change the selected columns.

:join_type

The type of join to use (passed to join_table). Defaults to :left_outer.

:qualify

The type of qualification to do, see join_table.

:select

An array of columns to select. When not used, selects all columns in the given dataset. When set to false, selects no columns and is like simply joining the tables, though graph keeps some metadata about the join that makes it important to use graph instead of join_table.

:table_alias

The alias to use for the table. If not specified, doesn't alias the table. You will get an error if the alias (or table) name is used more than once.

    # File lib/sequel/dataset/graph.rb
 53 def graph(dataset, join_conditions = nil, options = OPTS, &block)
 54   # Allow the use of a dataset or symbol as the first argument
 55   # Find the table name/dataset based on the argument
 56   table_alias = options[:table_alias]
 57   table = dataset
 58   create_dataset = true
 59 
 60   case dataset
 61   when Symbol
 62     # let alias be the same as the table name (sans any optional schema)
 63     # unless alias explicitly given in the symbol using ___ notation and symbol splitting is enabled
 64     table_alias ||= split_symbol(table).compact.last
 65   when Dataset
 66     if dataset.simple_select_all?
 67       table = dataset.opts[:from].first
 68       table_alias ||= table
 69     else
 70       table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
 71     end
 72     create_dataset = false
 73   when SQL::Identifier
 74     table_alias ||= table.value
 75   when SQL::QualifiedIdentifier
 76     table_alias ||= split_qualifiers(table).last
 77   when SQL::AliasedExpression
 78     return graph(table.expression, join_conditions, {:table_alias=>table.alias}.merge!(options), &block)
 79   else
 80     raise Error, "The dataset argument should be a symbol or dataset"
 81   end
 82   table_alias = table_alias.to_sym
 83 
 84   if create_dataset
 85     dataset = db.from(table)
 86   end
 87 
 88   # Raise Sequel::Error with explanation that the table alias has been used
 89   raise_alias_error = lambda do
 90     raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
 91       "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
 92   end
 93 
 94   # Only allow table aliases that haven't been used
 95   raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
 96   
 97   table_alias_qualifier = qualifier_from_alias_symbol(table_alias, table)
 98   implicit_qualifier = options[:implicit_qualifier]
 99   joined_dataset = joined_dataset?
100   ds = self
101   graph = opts[:graph]
102 
103   if !graph && (select = @opts[:select]) && !select.empty?
104     select_columns = nil
105 
106     unless !joined_dataset && select.length == 1 && (select[0].is_a?(SQL::ColumnAll))
107       force_from_self = false
108       select_columns = select.map do |sel|
109         unless col = _hash_key_symbol(sel)
110           force_from_self = true
111           break
112         end
113 
114         [sel, col]
115       end
116 
117       select_columns = nil if force_from_self
118     end
119   end
120 
121   # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs)
122   if (@opts[:graph_from_self] != false && !graph && (joined_dataset || force_from_self))
123     from_selfed = true
124     implicit_qualifier = options[:from_self_alias] || first_source
125     ds = ds.from_self(:alias=>implicit_qualifier)
126   end
127   
128   # Join the table early in order to avoid cloning the dataset twice
129   ds = ds.join_table(options[:join_type] || :left_outer, table, join_conditions, :table_alias=>table_alias_qualifier, :implicit_qualifier=>implicit_qualifier, :qualify=>options[:qualify], &block)
130 
131   return ds if options[:join_only]
132 
133   opts = ds.opts
134 
135   # Whether to include the table in the result set
136   add_table = options[:select] == false ? false : true
137 
138   if graph
139     graph = graph.dup
140     select = opts[:select].dup
141     [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
142   else
143     # Setup the initial graph data structure if it doesn't exist
144     qualifier = ds.first_source_alias
145     master = alias_symbol(qualifier)
146     raise_alias_error.call if master == table_alias
147 
148     # Master hash storing all .graph related information
149     graph = {}
150 
151     # Associates column aliases back to tables and columns
152     column_aliases = graph[:column_aliases] = {}
153 
154     # Associates table alias (the master is never aliased)
155     table_aliases = graph[:table_aliases] = {master=>self}
156 
157     # Keep track of the alias numbers used
158     ca_num = graph[:column_alias_num] = Hash.new(0)
159 
160     select = if select_columns
161       select_columns.map do |sel, column|
162         column_aliases[column] = [master, column]
163         if from_selfed
164           # Initial dataset was wrapped in subselect, selected all
165           # columns in the subselect, qualified by the subselect alias.
166           Sequel.qualify(qualifier, Sequel.identifier(column))
167         else
168           # Initial dataset not wrapped in subslect, just make
169           # sure columns are qualified in some way.
170           qualified_expression(sel, qualifier)
171         end
172       end
173     else
174       columns.map do |column|
175         column_aliases[column] = [master, column]
176         SQL::QualifiedIdentifier.new(qualifier, column)
177       end
178     end
179   end
180 
181   # Add the table alias to the list of aliases
182   # Even if it isn't been used in the result set,
183   # we add a key for it with a nil value so we can check if it
184   # is used more than once
185   table_aliases = graph[:table_aliases]
186   table_aliases[table_alias] = add_table ? dataset : nil
187 
188   # Add the columns to the selection unless we are ignoring them
189   if add_table
190     column_aliases = graph[:column_aliases]
191     ca_num = graph[:column_alias_num]
192     # Which columns to add to the result set
193     cols = options[:select] || dataset.columns
194     # If the column hasn't been used yet, don't alias it.
195     # If it has been used, try table_column.
196     # If that has been used, try table_column_N
197     # using the next value of N that we know hasn't been
198     # used
199     cols.each do |column|
200       col_alias, identifier = if column_aliases[column]
201         column_alias = :"#{table_alias}_#{column}"
202         if column_aliases[column_alias]
203           column_alias_num = ca_num[column_alias]
204           column_alias = :"#{column_alias}_#{column_alias_num}" 
205           ca_num[column_alias] += 1
206         end
207         [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)]
208       else
209         ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column)
210         [column, ident]
211       end
212       column_aliases[col_alias] = [table_alias, column].freeze
213       select.push(identifier)
214     end
215   end
216   [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k].freeze}
217   ds = ds.clone(:graph=>graph.freeze)
218   ds.select(*select)
219 end
set_graph_aliases(graph_aliases) click to toggle source

This allows you to manually specify the graph aliases to use when using graph. You can use it to only select certain columns, and have those columns mapped to specific aliases in the result set. This is the equivalent of select for a graphed dataset, and must be used instead of select whenever graphing is used.

graph_aliases should be a hash with keys being symbols of column aliases, and values being either symbols or arrays with one to three elements. If the value is a symbol, it is assumed to be the same as a one element array containing that symbol. The first element of the array should be the table alias symbol. The second should be the actual column name symbol. If the array only has a single element the column name symbol will be assumed to be the same as the corresponding hash key. If the array has a third element, it is used as the value returned, instead of table_alias.column_name.

DB[:artists].graph(:albums, :artist_id: :id).
  set_graph_aliases(name: :artists,
                    album_name: [:albums, :name],
                    forty_two: [:albums, :fourtwo, 42]).first
# SELECT artists.name, albums.name AS album_name, 42 AS forty_two ...
    # File lib/sequel/dataset/graph.rb
244 def set_graph_aliases(graph_aliases)
245   columns, graph_aliases = graph_alias_columns(graph_aliases)
246   if graph = opts[:graph]
247     select(*columns).clone(:graph => graph.merge(:column_aliases=>graph_aliases.freeze).freeze)
248   else
249     raise Error, "cannot call #set_graph_aliases on an ungraphed dataset"
250   end
251 end
ungraphed() click to toggle source

Remove the splitting of results into subhashes, and all metadata related to the current graph (if any).

    # File lib/sequel/dataset/graph.rb
255 def ungraphed
256   return self unless opts[:graph]
257   clone(:graph=>nil)
258 end

Private Instance Methods

graph_alias_columns(graph_aliases) click to toggle source

Transform the hash of graph aliases and return a two element array where the first element is an array of identifiers suitable to pass to a select method, and the second is a new hash of preprocessed graph aliases.

    # File lib/sequel/dataset/graph.rb
284 def graph_alias_columns(graph_aliases)
285   gas = {}
286   identifiers = graph_aliases.map do |col_alias, tc| 
287     table, column, value = Array(tc)
288     column ||= col_alias
289     gas[col_alias] = [table, column].freeze
290     identifier = value || SQL::QualifiedIdentifier.new(table, column)
291     identifier = SQL::AliasedExpression.new(identifier, col_alias) if value || column != col_alias
292     identifier
293   end
294   [identifiers, gas]
295 end
qualifier_from_alias_symbol(aliaz, identifier) click to toggle source

Wrap the alias symbol in an SQL::Identifier if the identifier on which is based is an SQL::Identifier. This works around cases where symbol splitting is enabled and the alias symbol contains double embedded underscores which would be considered an implicit qualified identifier if not wrapped in an SQL::Identifier.

    # File lib/sequel/dataset/graph.rb
266 def qualifier_from_alias_symbol(aliaz, identifier)
267   case identifier
268   when SQL::QualifiedIdentifier
269     if identifier.column.is_a?(String)
270       Sequel.identifier(aliaz)
271     else
272       aliaz
273     end
274   when SQL::Identifier
275     Sequel.identifier(aliaz)
276   else
277     aliaz
278   end
279 end

6 - Miscellaneous methods

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Attributes

cache[R]

Access the cache for the current dataset. Should be used with caution, as access to the cache is not thread safe without a mutex if other threads can reference the dataset. Symbol keys prefixed with an underscore are reserved for internal use.

db[R]

The database related to this dataset. This is the Database instance that will execute all of this dataset's queries.

opts[R]

The hash of options for this dataset, keys are symbols.

Public Class Methods

new(db) click to toggle source

Constructs a new Dataset instance with an associated database and options. Datasets are usually constructed by invoking the Database#[] method:

DB[:posts]

Sequel::Dataset is an abstract class that is not useful by itself. Each database adapter provides a subclass of Sequel::Dataset, and has the Database#dataset method return an instance of that subclass.

   # File lib/sequel/dataset/misc.rb
25 def initialize(db)
26   @db = db
27   @opts = OPTS
28   @cache = {}
29   freeze
30 end

Public Instance Methods

==(o) click to toggle source

Define a hash value such that datasets with the same class, DB, and opts will be considered equal.

   # File lib/sequel/dataset/misc.rb
34 def ==(o)
35   o.is_a?(self.class) && db == o.db && opts == o.opts
36 end
current_datetime() click to toggle source

An object representing the current date or time, should be an instance of Sequel.datetime_class.

   # File lib/sequel/dataset/misc.rb
40 def current_datetime
41   Sequel.datetime_class.now
42 end
dup() click to toggle source

Return self, as datasets are always frozen.

   # File lib/sequel/dataset/misc.rb
50 def dup
51   self
52 end
each_server() { |server(s)| ... } click to toggle source

Yield a dataset for each server in the connection pool that is tied to that server. Intended for use in sharded environments where all servers need to be modified with the same data:

DB[:configs].where(key: 'setting').each_server{|ds| ds.update(value: 'new_value')}
   # File lib/sequel/dataset/misc.rb
59 def each_server
60   db.servers.each{|s| yield server(s)}
61 end
eql?(o) click to toggle source

Alias for ==

   # File lib/sequel/dataset/misc.rb
45 def eql?(o)
46   self == o
47 end
escape_like(string) click to toggle source

Returns the string with the LIKE metacharacters (% and _) escaped. Useful for when the LIKE term is a user-provided string where metacharacters should not be recognized. Example:

ds.escape_like("foo\\%_") # 'foo\\\%\_'
   # File lib/sequel/dataset/misc.rb
68 def escape_like(string)
69   string.gsub(/[\\%_]/){|m| "\\#{m}"}
70 end
first_source() click to toggle source

Alias of first_source_alias

   # File lib/sequel/dataset/misc.rb
91 def first_source
92   first_source_alias
93 end
first_source_alias() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn't have a table, raises an Error. If the table is aliased, returns the aliased name.

DB[:table].first_source_alias
# => :table

DB[Sequel[:table].as(:t)].first_source_alias
# => :t
    # File lib/sequel/dataset/misc.rb
103 def first_source_alias
104   source = @opts[:from]
105   if source.nil? || source.empty?
106     raise Error, 'No source specified for query'
107   end
108   case s = source.first
109   when SQL::AliasedExpression
110     s.alias
111   when Symbol
112     _, _, aliaz = split_symbol(s)
113     aliaz ? aliaz.to_sym : s
114   else
115     s
116   end
117 end
first_source_table() click to toggle source

The first source (primary table) for this dataset. If the dataset doesn't have a table, raises an error. If the table is aliased, returns the original table, not the alias

DB[:table].first_source_table
# => :table

DB[Sequel[:table].as(:t)].first_source_table
# => :table
    # File lib/sequel/dataset/misc.rb
128 def first_source_table
129   source = @opts[:from]
130   if source.nil? || source.empty?
131     raise Error, 'No source specified for query'
132   end
133   case s = source.first
134   when SQL::AliasedExpression
135     s.expression
136   when Symbol
137     sch, table, aliaz = split_symbol(s)
138     aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
139   else
140     s
141   end
142 end
freeze() click to toggle source

Freeze the opts when freezing the dataset.

Calls superclass method
   # File lib/sequel/dataset/misc.rb
74 def freeze
75   @opts.freeze
76   super
77 end
hash() click to toggle source

Define a hash value such that datasets with the same class, DB, and opts, will have the same hash value.

    # File lib/sequel/dataset/misc.rb
146 def hash
147   [self.class, db, opts].hash
148 end
inspect() click to toggle source

Returns a string representation of the dataset including the class name and the corresponding SQL select statement.

    # File lib/sequel/dataset/misc.rb
152 def inspect
153   "#<#{visible_class_name}: #{sql.inspect}>"
154 end
joined_dataset?() click to toggle source

Whether this dataset is a joined dataset (multiple FROM tables or any JOINs).

    # File lib/sequel/dataset/misc.rb
157 def joined_dataset?
158  !!((opts[:from].is_a?(Array) && opts[:from].size > 1) || opts[:join])
159 end
placeholder_literalizer_class() click to toggle source

The class to use for placeholder literalizers for the current dataset.

    # File lib/sequel/dataset/misc.rb
162 def placeholder_literalizer_class
163   ::Sequel::Dataset::PlaceholderLiteralizer
164 end
placeholder_literalizer_loader(&block) click to toggle source

A placeholder literalizer loader for the current dataset.

    # File lib/sequel/dataset/misc.rb
167 def placeholder_literalizer_loader(&block)
168   placeholder_literalizer_class.loader(self, &block)
169 end
row_number_column() click to toggle source

The alias to use for the row_number column, used when emulating OFFSET support and for eager limit strategies

    # File lib/sequel/dataset/misc.rb
173 def row_number_column
174   :x_sequel_row_number_x
175 end
row_proc() click to toggle source

The row_proc for this database, should be any object that responds to call with a single hash argument and returns the object you want each to return.

    # File lib/sequel/dataset/misc.rb
179 def row_proc
180   @opts[:row_proc]
181 end
split_alias(c) click to toggle source

Splits a possible implicit alias in c, handling both SQL::AliasedExpressions and Symbols. Returns an array of two elements, with the first being the main expression, and the second being the alias.

    # File lib/sequel/dataset/misc.rb
186 def split_alias(c)
187   case c
188   when Symbol
189     c_table, column, aliaz = split_symbol(c)
190     [c_table ? SQL::QualifiedIdentifier.new(c_table, column.to_sym) : column.to_sym, aliaz]
191   when SQL::AliasedExpression
192     [c.expression, c.alias]
193   when SQL::JoinClause
194     [c.table, c.table_alias]
195   else
196     [c, nil]
197   end
198 end
unqualified_column_for(v) click to toggle source

This returns an SQL::Identifier or SQL::AliasedExpression containing an SQL identifier that represents the unqualified column for the given value. The given value should be a Symbol, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression containing one of those. In other cases, this returns nil.

    # File lib/sequel/dataset/misc.rb
205 def unqualified_column_for(v)
206   unless v.is_a?(String)
207     _unqualified_column_for(v)
208   end
209 end
unused_table_alias(table_alias, used_aliases = []) click to toggle source

Creates a unique table alias that hasn't already been used in the dataset. table_alias can be any type of object accepted by alias_symbol. The symbol returned will be the implicit alias in the argument, possibly appended with “_N” if the implicit alias has already been used, where N is an integer starting at 0 and increasing until an unused one is found.

You can provide a second addition array argument containing symbols that should not be considered valid table aliases. The current aliases for the FROM and JOIN tables are automatically included in this array.

DB[:table].unused_table_alias(:t)
# => :t

DB[:table].unused_table_alias(:table)
# => :table_0

DB[:table, :table_0].unused_table_alias(:table)
# => :table_1

DB[:table, :table_0].unused_table_alias(:table, [:table_1, :table_2])
# => :table_3
    # File lib/sequel/dataset/misc.rb
233 def unused_table_alias(table_alias, used_aliases = [])
234   table_alias = alias_symbol(table_alias)
235   used_aliases += opts[:from].map{|t| alias_symbol(t)} if opts[:from]
236   used_aliases += opts[:join].map{|j| j.table_alias ? alias_alias_symbol(j.table_alias) : alias_symbol(j.table)} if opts[:join]
237   if used_aliases.include?(table_alias)
238     i = 0
239     while true
240       ta = :"#{table_alias}_#{i}"
241       return ta unless used_aliases.include?(ta)
242       i += 1 
243     end
244   else
245     table_alias
246   end
247 end
with_quote_identifiers(v) click to toggle source

Return a modified dataset with quote_identifiers set.

    # File lib/sequel/dataset/misc.rb
250 def with_quote_identifiers(v)
251   clone(:quote_identifiers=>v, :skip_symbol_cache=>true)
252 end

Protected Instance Methods

_columns() click to toggle source

The cached columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
281 def _columns
282   cache_get(:_columns)
283 end
cache_get(k) click to toggle source

Retreive a value from the dataset's cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
263 def cache_get(k)
264   Sequel.synchronize{@cache[k]}
265 end
cache_set(k, v) click to toggle source

Set a value in the dataset's cache in a thread safe manner.

    # File lib/sequel/dataset/misc.rb
268 def cache_set(k, v)
269   Sequel.synchronize{@cache[k] = v}
270 end
clear_columns_cache() click to toggle source

Clear the columns hash for the current dataset. This is not a thread safe operation, so it should only be used if the dataset could not be used by another thread (such as one that was just created via clone).

    # File lib/sequel/dataset/misc.rb
276 def clear_columns_cache
277   @cache.delete(:_columns)
278 end

Private Instance Methods

_unqualified_column_for(v) click to toggle source

Internal recursive version of unqualified_column_for, handling Strings inside of other objects.

    # File lib/sequel/dataset/misc.rb
355 def _unqualified_column_for(v)
356   case v
357   when Symbol
358     _, c, a = Sequel.split_symbol(v)
359     c = Sequel.identifier(c)
360     a ? c.as(a) : c
361   when String
362     Sequel.identifier(v)
363   when SQL::Identifier
364     v
365   when SQL::QualifiedIdentifier
366     _unqualified_column_for(v.column)
367   when SQL::AliasedExpression
368     if expr = unqualified_column_for(v.expression)
369       SQL::AliasedExpression.new(expr, v.alias)
370     end
371   end
372 end
cached_dataset(key) { || ... } click to toggle source

Check the cache for the given key, returning the value. Otherwise, yield to get the dataset and cache the dataset under the given key.

    # File lib/sequel/dataset/misc.rb
289 def cached_dataset(key)
290   unless ds = cache_get(key)
291     ds = yield
292     cache_set(key, ds)
293   end
294 
295   ds
296 end
cached_placeholder_literalizer(key) { |pl| ... } click to toggle source

Return a cached placeholder literalizer for the given key if there is one for this dataset. If there isn't one, increment the counter for the number of calls for the key, and if the counter is at least three, then create a placeholder literalizer by yielding to the block, and cache it.

    # File lib/sequel/dataset/misc.rb
303 def cached_placeholder_literalizer(key)
304   if loader = cache_get(key)
305     return loader unless loader.is_a?(Integer)
306     loader += 1
307 
308     if loader >= 3
309       loader = placeholder_literalizer_loader{|pl, _| yield pl}
310       cache_set(key, loader)
311     else
312       cache_set(key, loader + 1)
313       loader = nil
314     end
315   elsif cache_sql? && supports_placeholder_literalizer?
316     cache_set(key, 1)
317   end
318 
319   loader
320 end
cached_where_placeholder_literalizer(where_args, where_block, key, &block) click to toggle source

Return a cached placeholder literalizer for the key, unless where_block is nil and where_args is an empty array or hash. This is designed to guard against placeholder literalizer use when passing arguments to where in the uncached case and filter_expr if a cached placeholder literalizer is used.

    # File lib/sequel/dataset/misc.rb
327 def cached_where_placeholder_literalizer(where_args, where_block, key, &block)
328   where_args = where_args[0] if where_args.length == 1
329   unless where_block
330     return if where_args == OPTS || where_args == EMPTY_ARRAY
331   end
332 
333   cached_placeholder_literalizer(key, &block)
334 end
columns=(v) click to toggle source

Set the columns for the current dataset.

    # File lib/sequel/dataset/misc.rb
337 def columns=(v)
338   cache_set(:_columns, v)
339 end
initialize_clone(c, _=nil) click to toggle source

Set the db, opts, and cache for the copy of the dataset.

    # File lib/sequel/dataset/misc.rb
342 def initialize_clone(c, _=nil)
343   @db = c.db
344   @opts = Hash[c.opts]
345   if cols = c.cache_get(:_columns)
346     @cache = {:_columns=>cols}
347   else
348     @cache = {}
349   end
350 end
Also aliased as: initialize_copy
initialize_copy(c, _=nil)
Alias for: initialize_clone
visible_class_name() click to toggle source

Return the class name for this dataset, but skip anonymous classes

    # File lib/sequel/dataset/misc.rb
375 def visible_class_name
376   c = self.class
377   c = c.superclass while c.name.nil? || c.name == ''
378   c.name
379 end

8 - Methods related to prepared statements or bound variables

↑ top

Constants

DEFAULT_PREPARED_STATEMENT_MODULE_METHODS
PREPARED_ARG_PLACEHOLDER
PREPARED_STATEMENT_MODULE_CODE

Private Class Methods

prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block) click to toggle source
   # File lib/sequel/dataset/prepared_statements.rb
20 def self.prepared_statements_module(code, mods, meths=DEFAULT_PREPARED_STATEMENT_MODULE_METHODS, &block)
21   code = PREPARED_STATEMENT_MODULE_CODE[code] || code
22 
23   Module.new do
24     Array(mods).each do |mod|
25       include mod
26     end
27 
28     if block
29       module_eval(&block)
30     end
31 
32     meths.each do |meth|
33       module_eval("def #{meth}(sql, opts=Sequel::OPTS) #{code}; super end", __FILE__, __LINE__)
34     end
35     private(*meths)
36   end
37 end

Public Instance Methods

bind(bind_vars=OPTS) click to toggle source

Set the bind variables to use for the call. If bind variables have already been set for this dataset, they are updated with the contents of bind_vars.

DB[:table].where(id: :$id).bind(id: 1).call(:first)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
332 def bind(bind_vars=OPTS)
333   bind_vars = if bv = @opts[:bind_vars]
334     bv.merge(bind_vars).freeze
335   else
336     if bind_vars.frozen?
337       bind_vars
338     else
339       Hash[bind_vars]
340     end
341   end
342 
343   clone(:bind_vars=>bind_vars)
344 end
call(type, bind_variables=OPTS, *values, &block) click to toggle source

For the given type (:select, :first, :insert, :insert_select, :update, :delete, or :single_value), run the sql with the bind variables specified in the hash. values is a hash passed to insert or update (if one of those types is used), which may contain placeholders.

DB[:table].where(id: :$id).call(:first, id: 1)
# SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
# => {:id=>1}
    # File lib/sequel/dataset/prepared_statements.rb
353 def call(type, bind_variables=OPTS, *values, &block)
354   to_prepared_statement(type, values, :extend=>bound_variable_modules).call(bind_variables, &block)
355 end
prepare(type, name, *values) click to toggle source

Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement.

This returns a clone of the dataset extended with PreparedStatementMethods, which you can call with the hash of bind variables to use. The prepared statement is also stored in the associated Database, where it can be called by name. The following usage is identical:

ps = DB[:table].where(name: :$name).prepare(:first, :select_by_name)

ps.call(name: 'Blah')
# SELECT * FROM table WHERE name = ? -- ('Blah')
# => {:id=>1, :name=>'Blah'}

DB.call(:select_by_name, name: 'Blah') # Same thing
    # File lib/sequel/dataset/prepared_statements.rb
373 def prepare(type, name, *values)
374   ps = to_prepared_statement(type, values, :name=>name, :extend=>prepared_statement_modules, :no_delayed_evaluations=>true)
375 
376   ps = if ps.send(:emulate_prepared_statements?)
377     ps = ps.with_extend(EmulatePreparedStatementMethods)
378     ps.send(:emulated_prepared_statement, type, name, values)
379   else
380     sql = ps.prepared_sql
381     ps.prepared_args.freeze
382     ps.clone(:prepared_sql=>sql, :sql=>sql)
383   end
384 
385   db.set_prepared_statement(name, ps)
386   ps
387 end

Protected Instance Methods

to_prepared_statement(type, values=nil, opts=OPTS) click to toggle source

Return a cloned copy of the current dataset extended with PreparedStatementMethods, setting the type and modify values.

    # File lib/sequel/dataset/prepared_statements.rb
393 def to_prepared_statement(type, values=nil, opts=OPTS)
394   mods = opts[:extend] || []
395   mods += [PreparedStatementMethods]
396 
397   bind.
398     clone(:prepared_statement_name=>opts[:name], :prepared_type=>type, :prepared_modify_values=>values, :orig_dataset=>self, :no_cache_sql=>true, :prepared_args=>@opts[:prepared_args]||[], :no_delayed_evaluations=>opts[:no_delayed_evaluations]).
399     with_extend(*mods)
400 end

Private Instance Methods

allow_preparing_prepared_statements?() click to toggle source

Don't allow preparing prepared statements by default.

    # File lib/sequel/dataset/prepared_statements.rb
405 def allow_preparing_prepared_statements?
406   false
407 end
bound_variable_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
409 def bound_variable_modules
410   prepared_statement_modules
411 end
emulate_prepared_statements?() click to toggle source

Whether prepared statements should be emulated. True by default so that adapters have to opt in.

    # File lib/sequel/dataset/prepared_statements.rb
415 def emulate_prepared_statements?
416   true
417 end
prepared_arg_placeholder() click to toggle source

The argument placeholder. Most databases used unnumbered arguments with question marks, so that is the default.

    # File lib/sequel/dataset/prepared_statements.rb
425 def prepared_arg_placeholder
426   PREPARED_ARG_PLACEHOLDER
427 end
prepared_statement_modules() click to toggle source
    # File lib/sequel/dataset/prepared_statements.rb
419 def prepared_statement_modules
420   []
421 end

9 - Internal Methods relating to SQL Creation

↑ top

Constants

BITWISE_METHOD_MAP
COUNT_FROM_SELF_OPTS
COUNT_OF_ALL_AS_COUNT
DEFAULT
EXISTS
IS_LITERALS
IS_OPERATORS
LIKE_OPERATORS
MERGE_NORMALIZE_TYPE_MAP
MERGE_TYPE_SQL

Mapping of merge types to related SQL

N_ARITY_OPERATORS
QUALIFY_KEYS
REGEXP_OPERATORS
TWO_ARITY_OPERATORS
WILDCARD

Public Class Methods

clause_methods(type, clauses) click to toggle source

Given a type (e.g. select) and an array of clauses, return an array of methods to call to build the SQL string.

    # File lib/sequel/dataset/sql.rb
225 def self.clause_methods(type, clauses)
226   clauses.map{|clause| :"#{type}_#{clause}_sql"}.freeze
227 end
def_sql_method(mod, type, clauses) click to toggle source

Define a dataset literalization method for the given type in the given module, using the given clauses.

Arguments:

mod

Module in which to define method

type

Type of SQL literalization method to create, either :select, :insert, :update, or :delete

clauses

array of clauses that make up the SQL query for the type. This can either be a single array of symbols/strings, or it can be an array of pairs, with the first element in each pair being an if/elsif/else code fragment, and the second element in each pair being an array of symbol/strings for the appropriate branch.

    # File lib/sequel/dataset/sql.rb
239 def self.def_sql_method(mod, type, clauses)
240   priv = type == :update || type == :insert
241   cacheable = type == :select || type == :delete
242 
243   lines = []
244   lines << 'private' if priv
245   lines << "def #{'_' if priv}#{type}_sql"
246   lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
247   lines << "if sql = cache_get(:_#{type}_sql); return sql end" if cacheable
248   lines << 'check_delete_allowed!' << 'check_not_limited!(:delete)' if type == :delete
249   lines << 'sql = @opts[:append_sql] || sql_string_origin'
250 
251   if clauses.all?{|c| c.is_a?(Array)}
252     clauses.each do |i, cs|
253       lines << i
254       lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 
255     end 
256     lines << 'end'
257   else
258     lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
259   end
260 
261   lines << "cache_set(:_#{type}_sql, sql) if cache_sql?" if cacheable
262   lines << 'sql'
263   lines << 'end'
264 
265   mod.class_eval lines.join("\n"), __FILE__, __LINE__
266 end

Public Instance Methods

aliased_expression_sql_append(sql, ae) click to toggle source

Append literalization of aliased expression to SQL string.

    # File lib/sequel/dataset/sql.rb
300 def aliased_expression_sql_append(sql, ae)
301   literal_append(sql, ae.expression)
302   as_sql_append(sql, ae.alias, ae.columns)
303 end
array_sql_append(sql, a) click to toggle source

Append literalization of array to SQL string.

    # File lib/sequel/dataset/sql.rb
306 def array_sql_append(sql, a)
307   if a.empty?
308     sql << '(NULL)'
309   else
310     sql << '('
311     expression_list_append(sql, a)
312     sql << ')'
313   end
314 end
boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
317 def boolean_constant_sql_append(sql, constant)
318   if (constant == true || constant == false) && !supports_where_true?
319     sql << (constant == true ? '(1 = 1)' : '(1 = 0)')
320   else
321     literal_append(sql, constant)
322   end
323 end
case_expression_sql_append(sql, ce) click to toggle source

Append literalization of case expression to SQL string.

    # File lib/sequel/dataset/sql.rb
326 def case_expression_sql_append(sql, ce)
327   sql << '(CASE'
328   if ce.expression?
329     sql << ' '
330     literal_append(sql, ce.expression)
331   end
332   w = " WHEN "
333   t = " THEN "
334   ce.conditions.each do |c,r|
335     sql << w
336     literal_append(sql, c)
337     sql << t
338     literal_append(sql, r)
339   end
340   sql << " ELSE "
341   literal_append(sql, ce.default)
342   sql << " END)"
343 end
cast_sql_append(sql, expr, type) click to toggle source

Append literalization of cast expression to SQL string.

    # File lib/sequel/dataset/sql.rb
346 def cast_sql_append(sql, expr, type)
347   sql << 'CAST('
348   literal_append(sql, expr)
349   sql << ' AS ' << db.cast_type_literal(type).to_s
350   sql << ')'
351 end
column_all_sql_append(sql, ca) click to toggle source

Append literalization of column all selection to SQL string.

    # File lib/sequel/dataset/sql.rb
354 def column_all_sql_append(sql, ca)
355   qualified_identifier_sql_append(sql, ca.table, WILDCARD)
356 end
complex_expression_sql_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string.

    # File lib/sequel/dataset/sql.rb
359 def complex_expression_sql_append(sql, op, args)
360   case op
361   when *IS_OPERATORS
362     r = args[1]
363     if r.nil? || supports_is_true?
364       raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r]
365       sql << '('
366       literal_append(sql, args[0])
367       sql << ' ' << op.to_s << ' '
368       sql << val << ')'
369     elsif op == :IS
370       complex_expression_sql_append(sql, :"=", args)
371     else
372       complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new(:"!=", *args), SQL::BooleanExpression.new(:IS, args[0], nil)])
373     end
374   when :IN, :"NOT IN"
375     cols = args[0]
376     vals = args[1]
377     col_array = true if cols.is_a?(Array)
378     if vals.is_a?(Array)
379       val_array = true
380       empty_val_array = vals == []
381     end
382     if empty_val_array
383       literal_append(sql, empty_array_value(op, cols))
384     elsif col_array
385       if !supports_multiple_column_in?
386         if val_array
387           expr = SQL::BooleanExpression.new(:OR, *vals.to_a.map{|vs| SQL::BooleanExpression.from_value_pairs(cols.to_a.zip(vs).map{|c, v| [c, v]})})
388           literal_append(sql, op == :IN ? expr : ~expr)
389         else
390           old_vals = vals
391           vals = vals.naked if vals.is_a?(Sequel::Dataset)
392           vals = vals.to_a
393           val_cols = old_vals.columns
394           complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
395         end
396       else
397         # If the columns and values are both arrays, use array_sql instead of
398         # literal so that if values is an array of two element arrays, it
399         # will be treated as a value list instead of a condition specifier.
400         sql << '('
401         literal_append(sql, cols)
402         sql << ' ' << op.to_s << ' '
403         if val_array
404           array_sql_append(sql, vals)
405         else
406           literal_append(sql, vals)
407         end
408         sql << ')'
409       end
410     else
411       sql << '('
412       literal_append(sql, cols)
413       sql << ' ' << op.to_s << ' '
414       literal_append(sql, vals)
415       sql << ')'
416     end
417   when :LIKE, :'NOT LIKE'
418     sql << '('
419     literal_append(sql, args[0])
420     sql << ' ' << op.to_s << ' '
421     literal_append(sql, args[1])
422     if requires_like_escape?
423       sql << " ESCAPE "
424       literal_append(sql, "\\")
425     end
426     sql << ')'
427   when :ILIKE, :'NOT ILIKE'
428     complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : :"NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
429   when :**
430     function_sql_append(sql, Sequel.function(:power, *args))
431   when *TWO_ARITY_OPERATORS
432     if REGEXP_OPERATORS.include?(op) && !supports_regexp?
433       raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
434     end
435     sql << '('
436     literal_append(sql, args[0])
437     sql << ' ' << op.to_s << ' '
438     literal_append(sql, args[1])
439     sql << ')'
440   when *N_ARITY_OPERATORS
441     sql << '('
442     c = false
443     op_str = " #{op} "
444     args.each do |a|
445       sql << op_str if c
446       literal_append(sql, a)
447       c ||= true
448     end
449     sql << ')'
450   when :NOT
451     sql << 'NOT '
452     literal_append(sql, args[0])
453   when :NOOP
454     literal_append(sql, args[0])
455   when :'B~'
456     sql << '~'
457     literal_append(sql, args[0])
458   when :extract
459     sql << 'extract(' << args[0].to_s << ' FROM '
460     literal_append(sql, args[1])
461     sql << ')'
462   else
463     raise(InvalidOperation, "invalid operator #{op}")
464   end
465 end
constant_sql_append(sql, constant) click to toggle source

Append literalization of constant to SQL string.

    # File lib/sequel/dataset/sql.rb
468 def constant_sql_append(sql, constant)
469   sql << constant.to_s
470 end
delayed_evaluation_sql_append(sql, delay) click to toggle source

Append literalization of delayed evaluation to SQL string, causing the delayed evaluation proc to be evaluated.

    # File lib/sequel/dataset/sql.rb
474 def delayed_evaluation_sql_append(sql, delay)
475   # Delayed evaluations are used specifically so the SQL
476   # can differ in subsequent calls, so we definitely don't
477   # want to cache the sql in this case.
478   disable_sql_caching!
479 
480   if recorder = @opts[:placeholder_literalizer]
481     recorder.use(sql, lambda{delay.call(self)}, nil)
482   else
483     literal_append(sql, delay.call(self))
484   end
485 end
function_sql_append(sql, f) click to toggle source

Append literalization of function call to SQL string.

    # File lib/sequel/dataset/sql.rb
488 def function_sql_append(sql, f)
489   name = f.name
490   opts = f.opts
491 
492   if opts[:emulate]
493     if emulate_function?(name)
494       emulate_function_sql_append(sql, f)
495       return
496     end
497 
498     name = native_function_name(name) 
499   end
500 
501   sql << 'LATERAL ' if opts[:lateral]
502 
503   case name
504   when SQL::Identifier
505     if supports_quoted_function_names? && opts[:quoted]
506       literal_append(sql, name)
507     else
508       sql << name.value.to_s
509     end
510   when SQL::QualifiedIdentifier
511     if supports_quoted_function_names? && opts[:quoted] != false
512       literal_append(sql, name)
513     else
514       sql << split_qualifiers(name).join('.')
515     end
516   else
517     if supports_quoted_function_names? && opts[:quoted]
518       quote_identifier_append(sql, name)
519     else
520       sql << name.to_s
521     end
522   end
523 
524   sql << '('
525   if filter = opts[:filter]
526     filter = filter_expr(filter, &opts[:filter_block])
527   end
528   if opts[:*]
529     if filter && !supports_filtered_aggregates?
530       literal_append(sql, Sequel.case({filter=>1}, nil))
531       filter = nil
532     else
533       sql <<  '*'
534     end
535   else
536     sql << "DISTINCT " if opts[:distinct]
537     if filter && !supports_filtered_aggregates?
538       expression_list_append(sql, f.args.map{|arg| Sequel.case({filter=>arg}, nil)})
539       filter = nil
540     else
541       expression_list_append(sql, f.args)
542     end
543     if order = opts[:order]
544       sql << " ORDER BY "
545       expression_list_append(sql, order)
546     end
547   end
548   sql << ')'
549 
550   if group = opts[:within_group]
551     sql << " WITHIN GROUP (ORDER BY "
552     expression_list_append(sql, group)
553     sql << ')'
554   end
555 
556   if filter
557     sql << " FILTER (WHERE "
558     literal_append(sql, filter)
559     sql << ')'
560   end
561 
562   if window = opts[:over]
563     sql << ' OVER '
564     window_sql_append(sql, window.opts)
565   end
566 
567   if opts[:with_ordinality]
568     sql << " WITH ORDINALITY"
569   end
570 end
join_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN clause without ON or USING to SQL string.

    # File lib/sequel/dataset/sql.rb
573 def join_clause_sql_append(sql, jc)
574   table = jc.table
575   table_alias = jc.table_alias
576   table_alias = nil if table == table_alias && !jc.column_aliases
577   sql << ' ' << join_type_sql(jc.join_type) << ' '
578   identifier_append(sql, table)
579   as_sql_append(sql, table_alias, jc.column_aliases) if table_alias
580 end
join_on_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN ON clause to SQL string.

    # File lib/sequel/dataset/sql.rb
583 def join_on_clause_sql_append(sql, jc)
584   join_clause_sql_append(sql, jc)
585   sql << ' ON '
586   literal_append(sql, filter_expr(jc.on))
587 end
join_using_clause_sql_append(sql, jc) click to toggle source

Append literalization of JOIN USING clause to SQL string.

    # File lib/sequel/dataset/sql.rb
590 def join_using_clause_sql_append(sql, jc)
591   join_clause_sql_append(sql, jc)
592   join_using_clause_using_sql_append(sql, jc.using) 
593 end
negative_boolean_constant_sql_append(sql, constant) click to toggle source

Append literalization of negative boolean constant to SQL string.

    # File lib/sequel/dataset/sql.rb
596 def negative_boolean_constant_sql_append(sql, constant)
597   sql << 'NOT '
598   boolean_constant_sql_append(sql, constant)
599 end
ordered_expression_sql_append(sql, oe) click to toggle source

Append literalization of ordered expression to SQL string.

    # File lib/sequel/dataset/sql.rb
602 def ordered_expression_sql_append(sql, oe)
603   if emulate = requires_emulating_nulls_first?
604     case oe.nulls
605     when :first
606       null_order = 0
607     when :last
608       null_order = 2
609     end
610 
611     if null_order
612       literal_append(sql, Sequel.case({{oe.expression=>nil}=>null_order}, 1))
613       sql << ", "
614     end
615   end
616 
617   literal_append(sql, oe.expression)
618   sql << (oe.descending ? ' DESC' : ' ASC')
619 
620   unless emulate
621     case oe.nulls
622     when :first
623       sql << " NULLS FIRST"
624     when :last
625       sql << " NULLS LAST"
626     end
627   end
628 end
placeholder_literal_string_sql_append(sql, pls) click to toggle source

Append literalization of placeholder literal string to SQL string.

    # File lib/sequel/dataset/sql.rb
631 def placeholder_literal_string_sql_append(sql, pls)
632   args = pls.args
633   str = pls.str
634   sql << '(' if pls.parens
635   if args.is_a?(Hash)
636     if args.empty?
637       sql << str
638     else
639       re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
640       while true
641         previous, q, str = str.partition(re)
642         sql << previous
643         literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
644         break if str.empty?
645       end
646     end
647   elsif str.is_a?(Array)
648     len = args.length
649     str.each_with_index do |s, i|
650       sql << s
651       literal_append(sql, args[i]) unless i == len
652     end
653     unless str.length == args.length || str.length == args.length + 1
654       raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
655     end
656   else
657     i = -1
658     match_len = args.length - 1
659     while true
660       previous, q, str = str.partition('?')
661       sql << previous
662       literal_append(sql, args.at(i+=1)) unless q.empty?
663       if str.empty?
664         unless i == match_len
665           raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder string"
666         end
667         break
668       end
669     end
670   end
671   sql << ')' if pls.parens
672 end
qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c)) click to toggle source

Append literalization of qualified identifier to SQL string. If 3 arguments are given, the 2nd should be the table/qualifier and the third should be column/qualified. If 2 arguments are given, the 2nd should be an SQL::QualifiedIdentifier.

    # File lib/sequel/dataset/sql.rb
677 def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
678   identifier_append(sql, table)
679   sql << '.'
680   identifier_append(sql, column)
681 end
quote_identifier_append(sql, name) click to toggle source

Append literalization of unqualified identifier to SQL string. Adds quoting to identifiers (columns and tables). If identifiers are not being quoted, returns name as a string. If identifiers are being quoted quote the name with quoted_identifier.

    # File lib/sequel/dataset/sql.rb
687 def quote_identifier_append(sql, name)
688   if name.is_a?(LiteralString)
689     sql << name
690   else
691     name = name.value if name.is_a?(SQL::Identifier)
692     name = input_identifier(name)
693     if quote_identifiers?
694       quoted_identifier_append(sql, name)
695     else
696       sql << name
697     end
698   end
699 end
quote_schema_table_append(sql, table) click to toggle source

Append literalization of identifier or unqualified identifier to SQL string.

    # File lib/sequel/dataset/sql.rb
702 def quote_schema_table_append(sql, table)
703   schema, table = schema_and_table(table)
704   if schema
705     quote_identifier_append(sql, schema)
706     sql << '.'
707   end
708   quote_identifier_append(sql, table)
709 end
quoted_identifier_append(sql, name) click to toggle source

Append literalization of quoted identifier to SQL string. This method quotes the given name with the SQL standard double quote. should be overridden by subclasses to provide quoting not matching the SQL standard, such as backtick (used by MySQL and SQLite).

    # File lib/sequel/dataset/sql.rb
715 def quoted_identifier_append(sql, name)
716   sql << '"' << name.to_s.gsub('"', '""') << '"'
717 end
schema_and_table(table_name, sch=nil) click to toggle source

Split the schema information from the table, returning two strings, one for the schema and one for the table. The returned schema may be nil, but the table will always have a string value.

Note that this function does not handle tables with more than one level of qualification (e.g. database.schema.table on Microsoft SQL Server).

    # File lib/sequel/dataset/sql.rb
726 def schema_and_table(table_name, sch=nil)
727   sch = sch.to_s if sch
728   case table_name
729   when Symbol
730     s, t, _ = split_symbol(table_name)
731     [s||sch, t]
732   when SQL::QualifiedIdentifier
733     [table_name.table.to_s, table_name.column.to_s]
734   when SQL::Identifier
735     [sch, table_name.value.to_s]
736   when String
737     [sch, table_name]
738   else
739     raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
740   end
741 end
split_qualifiers(table_name, *args) click to toggle source

Splits table_name into an array of strings.

ds.split_qualifiers(:s) # ['s']
ds.split_qualifiers(Sequel[:t][:s]) # ['t', 's']
ds.split_qualifiers(Sequel[:d][:t][:s]) # ['d', 't', 's']
ds.split_qualifiers(Sequel.qualify(Sequel[:h][:d], Sequel[:t][:s])) # ['h', 'd', 't', 's']
    # File lib/sequel/dataset/sql.rb
749 def split_qualifiers(table_name, *args)
750   case table_name
751   when SQL::QualifiedIdentifier
752     split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
753   else
754     sch, table = schema_and_table(table_name, *args)
755     sch ? [sch, table] : [table]
756   end
757 end
subscript_sql_append(sql, s) click to toggle source

Append literalization of subscripts (SQL array accesses) to SQL string.

    # File lib/sequel/dataset/sql.rb
760 def subscript_sql_append(sql, s)
761   case s.expression
762   when Symbol, SQL::Subscript, SQL::Identifier, SQL::QualifiedIdentifier
763     # nothing
764   else
765     wrap_expression = true
766     sql << '('
767   end
768   literal_append(sql, s.expression)
769   if wrap_expression
770     sql << ')['
771   else
772     sql << '['
773   end
774   sub = s.sub
775   if sub.length == 1 && (range = sub.first).is_a?(Range)
776     literal_append(sql, range.begin)
777     sql << ':'
778     e = range.end
779     e -= 1 if range.exclude_end? && e.is_a?(Integer)
780     literal_append(sql, e)
781   else
782     expression_list_append(sql, s.sub)
783   end
784   sql << ']'
785 end
window_sql_append(sql, opts) click to toggle source

Append literalization of windows (for window functions) to SQL string.

    # File lib/sequel/dataset/sql.rb
788 def window_sql_append(sql, opts)
789   raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
790   space = false
791   space_s = ' '
792 
793   sql << '('
794 
795   if window = opts[:window]
796     literal_append(sql, window)
797     space = true
798   end
799 
800   if part = opts[:partition]
801     sql << space_s if space
802     sql << "PARTITION BY "
803     expression_list_append(sql, Array(part))
804     space = true
805   end
806 
807   if order = opts[:order]
808     sql << space_s if space
809     sql << "ORDER BY "
810     expression_list_append(sql, Array(order))
811     space = true
812   end
813 
814   if frame = opts[:frame]
815     sql << space_s if space
816 
817     if frame.is_a?(String)
818       sql << frame
819     else
820       case frame
821       when :all
822         frame_type = :rows
823         frame_start = :preceding
824         frame_end = :following
825       when :rows, :range, :groups
826         frame_type = frame
827         frame_start = :preceding
828         frame_end = :current
829       when Hash
830         frame_type = frame[:type]
831         unless frame_type == :rows || frame_type == :range || frame_type == :groups
832           raise Error, "invalid window :frame :type option: #{frame_type.inspect}"
833         end
834         unless frame_start = frame[:start]
835           raise Error, "invalid window :frame :start option: #{frame_start.inspect}"
836         end
837         frame_end = frame[:end]
838         frame_exclude = frame[:exclude]
839       else
840         raise Error, "invalid window :frame option: #{frame.inspect}"
841       end
842 
843       sql << frame_type.to_s.upcase << " "
844       sql << 'BETWEEN ' if frame_end
845       window_frame_boundary_sql_append(sql, frame_start, :preceding)
846       if frame_end
847         sql << " AND "
848         window_frame_boundary_sql_append(sql, frame_end, :following)
849       end
850 
851       if frame_exclude
852         sql << " EXCLUDE "
853 
854         case frame_exclude
855         when :current
856           sql << "CURRENT ROW"
857         when :group
858           sql << "GROUP"
859         when :ties
860           sql << "TIES"
861         when :no_others
862           sql << "NO OTHERS"
863         else
864           raise Error, "invalid window :frame :exclude option: #{frame_exclude.inspect}"
865         end
866       end
867     end
868   end
869 
870   sql << ')'
871 end

Protected Instance Methods

compound_from_self() click to toggle source

Return a from_self dataset if an order or limit is specified, so it works as expected with UNION, EXCEPT, and INTERSECT clauses.

    # File lib/sequel/dataset/sql.rb
877 def compound_from_self
878   (@opts[:sql] || @opts[:limit] || @opts[:order] || @opts[:offset]) ? from_self : self
879 end

Private Instance Methods

_check_modification_allowed!(modifying_joins_supported) click to toggle source

Internals of the check_*_allowed! methods

     # File lib/sequel/dataset/sql.rb
1071 def _check_modification_allowed!(modifying_joins_supported)
1072   raise(InvalidOperation, "Grouped datasets cannot be modified") if opts[:group]
1073   raise(InvalidOperation, "Joined datasets cannot be modified") if !modifying_joins_supported && joined_dataset?
1074 end
_insert_columns_sql(sql, columns) click to toggle source
     # File lib/sequel/dataset/sql.rb
1286 def _insert_columns_sql(sql, columns)
1287   if columns && !columns.empty?
1288     sql << ' ('
1289     identifier_list_append(sql, columns)
1290     sql << ')'
1291   end 
1292 end
_insert_values_sql(sql, values) click to toggle source
     # File lib/sequel/dataset/sql.rb
1308 def _insert_values_sql(sql, values)
1309   case values
1310   when Array
1311     if values.empty?
1312       sql << " DEFAULT VALUES"
1313     else
1314       sql << " VALUES "
1315       literal_append(sql, values)
1316     end
1317   when Dataset
1318     sql << ' '
1319     subselect_sql_append(sql, values)
1320   when LiteralString
1321     sql << ' ' << values
1322   else
1323     raise Error, "Unsupported INSERT values type, should be an Array or Dataset: #{values.inspect}"
1324   end
1325 end
_merge_delete_sql(sql, data) click to toggle source
    # File lib/sequel/dataset/sql.rb
896 def _merge_delete_sql(sql, data)
897   sql << " THEN DELETE"
898 end
_merge_insert_sql(sql, data) click to toggle source

Append the INSERT sql used in a MERGE

    # File lib/sequel/dataset/sql.rb
884 def _merge_insert_sql(sql, data)
885   sql << " THEN INSERT"
886   columns, values = _parse_insert_sql_args(data[:values])
887   _insert_columns_sql(sql, columns)
888   _insert_values_sql(sql, values)
889 end
_merge_update_sql(sql, data) click to toggle source
    # File lib/sequel/dataset/sql.rb
891 def _merge_update_sql(sql, data)
892   sql << " THEN UPDATE SET "
893   update_sql_values_hash(sql, data[:values])
894 end
_merge_when_conditions_sql(sql, data) click to toggle source

Append MERGE WHEN conditions, if there are conditions provided.

    # File lib/sequel/dataset/sql.rb
935 def _merge_when_conditions_sql(sql, data)
936   if data.has_key?(:conditions)
937     sql << " AND "
938     literal_append(sql, data[:conditions])
939   end
940 end
_merge_when_sql(sql) click to toggle source

Add the WHEN clauses to the MERGE SQL

    # File lib/sequel/dataset/sql.rb
923 def _merge_when_sql(sql)
924   raise Error, "no WHEN [NOT] MATCHED clauses provided for MERGE" unless merge_when = @opts[:merge_when]
925   merge_when.each do |data|
926     type = data[:type]
927     sql << MERGE_TYPE_SQL[type]
928     type = MERGE_NORMALIZE_TYPE_MAP[type] || type
929     _merge_when_conditions_sql(sql, data)
930     send(:"_merge_#{type}_sql", sql, data)
931   end
932 end
_parse_insert_sql_args(values) click to toggle source

Parse the values passed to insert_sql, returning columns and values to use for the INSERT. Returned columns is always an array, but can be empty for an INSERT without explicit column references. Returned values can be an array, dataset, or literal string.

    # File lib/sequel/dataset/sql.rb
946 def _parse_insert_sql_args(values)
947   columns = []
948 
949   case values.size
950   when 0
951     values = []
952   when 1
953     case vals = values[0]
954     when Hash
955       values = []
956       vals.each do |k,v| 
957         columns << k
958         values << v
959       end
960     when Dataset, Array, LiteralString
961       values = vals
962     end
963   when 2
964     if (v0 = values[0]).is_a?(Array) && ((v1 = values[1]).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
965       columns, values = v0, v1
966       raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
967     end
968   end
969 
970   [columns, values]
971 end
_truncate_sql(table) click to toggle source

Formats the truncate statement. Assumes the table given has already been literalized.

    # File lib/sequel/dataset/sql.rb
975 def _truncate_sql(table)
976   "TRUNCATE TABLE #{table}"
977 end
aggreate_dataset_use_from_self?() click to toggle source

Whether to use from_self for an aggregate dataset.

     # File lib/sequel/dataset/sql.rb
1024 def aggreate_dataset_use_from_self?
1025   options_overlap(COUNT_FROM_SELF_OPTS)
1026 end
aggregate_dataset() click to toggle source

Clone of this dataset usable in aggregate operations. Does a from_self if dataset contains any parameters that would affect normal aggregation, or just removes an existing order if not. Also removes the row_proc, which isn't needed for aggregate calculations.

     # File lib/sequel/dataset/sql.rb
1019 def aggregate_dataset
1020   (aggreate_dataset_use_from_self? ? from_self : unordered).naked
1021 end
alias_alias_symbol(s) click to toggle source

Returns an appropriate symbol for the alias represented by s.

    # File lib/sequel/dataset/sql.rb
980 def alias_alias_symbol(s)
981   case s
982   when Symbol
983     s
984   when String
985     s.to_sym
986   when SQL::Identifier
987     s.value.to_s.to_sym
988   else
989     raise Error, "Invalid alias for alias_alias_symbol: #{s.inspect}"
990   end
991 end
alias_symbol(sym) click to toggle source

Returns an appropriate alias symbol for the given object, which can be a Symbol, String, SQL::Identifier, SQL::QualifiedIdentifier, or SQL::AliasedExpression.

     # File lib/sequel/dataset/sql.rb
 996 def alias_symbol(sym)
 997   case sym
 998   when Symbol
 999     s, t, a = split_symbol(sym)
1000     a || s ? (a || t).to_sym : sym
1001   when String
1002     sym.to_sym
1003   when SQL::Identifier
1004     sym.value.to_s.to_sym
1005   when SQL::QualifiedIdentifier
1006     alias_symbol(sym.column)
1007   when SQL::AliasedExpression
1008     alias_alias_symbol(sym.alias)
1009   else
1010     raise Error, "Invalid alias for alias_symbol: #{sym.inspect}"
1011   end
1012 end
as_sql_append(sql, aliaz, column_aliases=nil) click to toggle source

Append aliasing expression to SQL string.

     # File lib/sequel/dataset/sql.rb
1029 def as_sql_append(sql, aliaz, column_aliases=nil)
1030   sql << ' AS '
1031   quote_identifier_append(sql, aliaz)
1032   if column_aliases
1033     raise Error, "#{db.database_type} does not support derived column lists" unless supports_derived_column_lists?
1034     sql << '('
1035     derived_column_list_sql_append(sql, column_aliases)
1036     sql << ')'
1037   end
1038 end
cache_sql?() click to toggle source

Don't allow caching SQL if specifically marked not to.

     # File lib/sequel/dataset/sql.rb
1041 def cache_sql?
1042   !@opts[:no_cache_sql] && !cache_get(:_no_cache_sql)
1043 end
check_delete_allowed!() click to toggle source

Check whether it is allowed to delete from this dataset.

     # File lib/sequel/dataset/sql.rb
1061 def check_delete_allowed!
1062   _check_modification_allowed!(supports_deleting_joins?)
1063 end
check_insert_allowed!() click to toggle source

Check whether it is allowed to insert into this dataset.

     # File lib/sequel/dataset/sql.rb
1055 def check_insert_allowed!
1056   _check_modification_allowed!(false)
1057 end
Also aliased as: check_truncation_allowed!
check_modification_allowed!() click to toggle source

Raise an InvalidOperation exception if modification is not allowed for this dataset. Check whether it is allowed to insert into this dataset. Only for backwards compatibility with older external adapters.

     # File lib/sequel/dataset/sql.rb
1048 def check_modification_allowed!
1049   # SEQUEL6: Remove
1050   Sequel::Deprecation.deprecate("Dataset#check_modification_allowed!", "Use check_{insert,delete,update,truncation}_allowed! instead")
1051   _check_modification_allowed!(supports_modifying_joins?)
1052 end
check_not_limited!(type) click to toggle source

Raise error if the dataset uses limits or offsets.

     # File lib/sequel/dataset/sql.rb
1077 def check_not_limited!(type)
1078   return if @opts[:skip_limit_check] && type != :truncate
1079   raise InvalidOperation, "Dataset##{type} not supported on datasets with limits or offsets" if opts[:limit] || opts[:offset]
1080 end
check_truncation_allowed!()
check_update_allowed!() click to toggle source

Check whether it is allowed to update this dataset.

     # File lib/sequel/dataset/sql.rb
1066 def check_update_allowed!
1067   _check_modification_allowed!(supports_updating_joins?)
1068 end
column_list_append(sql, columns) click to toggle source

Append column list to SQL string. If the column list is empty, a wildcard (*) is appended.

     # File lib/sequel/dataset/sql.rb
1084 def column_list_append(sql, columns)
1085   if (columns.nil? || columns.empty?)
1086     sql << '*'
1087   else
1088     expression_list_append(sql, columns)
1089   end
1090 end
complex_expression_arg_pairs(args) { |args, args| ... } click to toggle source

Yield each pair of arguments to the block, which should return an object representing the SQL expression for those two arguments. For more than two arguments, the first argument to the block will be result of the previous block call.

     # File lib/sequel/dataset/sql.rb
1096 def complex_expression_arg_pairs(args)
1097   case args.length
1098   when 1
1099     args[0]
1100   when 2
1101     yield args[0], args[1]
1102   else
1103     args.inject{|m, a| yield(m, a)}
1104   end
1105 end
complex_expression_arg_pairs_append(sql, args, &block) click to toggle source

Append the literalization of the args using complex_expression_arg_pairs to the given SQL string, used when database operator/function is 2-ary where Sequel expression is N-ary.

     # File lib/sequel/dataset/sql.rb
1110 def complex_expression_arg_pairs_append(sql, args, &block)
1111   literal_append(sql, complex_expression_arg_pairs(args, &block))
1112 end
complex_expression_emulate_append(sql, op, args) click to toggle source

Append literalization of complex expression to SQL string, for operators unsupported by some databases. Used by adapters for databases that don't support the operators natively.

     # File lib/sequel/dataset/sql.rb
1117 def complex_expression_emulate_append(sql, op, args)
1118   # :nocov:
1119   case op
1120   # :nocov:
1121   when :%
1122     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(:MOD, a, b)}
1123   when :>>
1124     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel./(a, Sequel.function(:power, 2, b))}
1125   when :<<
1126     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.*(a, Sequel.function(:power, 2, b))}
1127   when :&, :|, :^
1128     f = BITWISE_METHOD_MAP[op]
1129     complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.function(f, a, b)}
1130   when :'B~'
1131     sql << "((0 - "
1132     literal_append(sql, args[0])
1133     sql << ") - 1)"
1134   end
1135 end
compound_dataset_sql_append(sql, ds) click to toggle source

Append literalization of dataset used in UNION/INTERSECT/EXCEPT clause to SQL string.

     # File lib/sequel/dataset/sql.rb
1138 def compound_dataset_sql_append(sql, ds)
1139   subselect_sql_append(sql, ds)
1140 end
dataset_alias(number) click to toggle source

The alias to use for datasets, takes a number to make sure the name is unique.

     # File lib/sequel/dataset/sql.rb
1143 def dataset_alias(number)
1144   :"t#{number}"
1145 end
default_time_format() click to toggle source

The strftime format to use when literalizing time (Sequel::SQLTime) values.

     # File lib/sequel/dataset/sql.rb
1148 def default_time_format
1149   "'%H:%M:%S.%6N'"
1150 end
default_timestamp_format() click to toggle source

The strftime format to use when literalizing timestamp (Time/DateTime) values.

     # File lib/sequel/dataset/sql.rb
1153 def default_timestamp_format
1154   "'%Y-%m-%d %H:%M:%S.%6N'"
1155 end
delete_delete_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1157 def delete_delete_sql(sql)
1158   sql << 'DELETE'
1159 end
delete_from_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1161 def delete_from_sql(sql)
1162   if f = @opts[:from]
1163     sql << ' FROM '
1164     source_list_append(sql, f)
1165   end
1166 end
delete_order_sql(sql)
Alias for: select_order_sql
delete_returning_sql(sql)
delete_where_sql(sql)
Alias for: select_where_sql
delete_with_sql(sql)
Alias for: select_with_sql
derived_column_list_sql_append(sql, column_aliases) click to toggle source

Append the column aliases to the SQL.

     # File lib/sequel/dataset/sql.rb
1169 def derived_column_list_sql_append(sql, column_aliases)
1170   identifier_list_append(sql, column_aliases)
1171 end
disable_sql_caching!() click to toggle source

Disable caching of SQL for the current dataset

     # File lib/sequel/dataset/sql.rb
1174 def disable_sql_caching!
1175   cache_set(:_no_cache_sql, true)
1176 end
empty_array_value(op, cols) click to toggle source

An expression for how to handle an empty array lookup.

     # File lib/sequel/dataset/sql.rb
1218 def empty_array_value(op, cols)
1219   {1 => ((op == :IN) ? 0 : 1)}
1220 end
empty_from_sql() click to toggle source

An SQL FROM clause to use in SELECT statements where the dataset has no from tables.

     # File lib/sequel/dataset/sql.rb
1180 def empty_from_sql
1181   nil
1182 end
emulate_function?(name) click to toggle source

Whether to emulate the function with the given name. This should only be true if the emulation goes beyond choosing a function with a different name.

     # File lib/sequel/dataset/sql.rb
1186 def emulate_function?(name)
1187   false
1188 end
expression_list_append(sql, columns) click to toggle source

Append literalization of array of expressions to SQL string, separating them with commas.

     # File lib/sequel/dataset/sql.rb
1192 def expression_list_append(sql, columns)
1193   c = false
1194   co = ', '
1195   columns.each do |col|
1196     sql << co if c
1197     literal_append(sql, col)
1198     c ||= true
1199   end
1200 end
format_timestamp(v) click to toggle source

Format the timestamp based on the default_timestamp_format.

     # File lib/sequel/dataset/sql.rb
1223 def format_timestamp(v)
1224   db.from_application_timestamp(v).strftime(default_timestamp_format)
1225 end
format_timestamp_usec(usec, ts=timestamp_precision) click to toggle source

Return the SQL timestamp fragment to use for the fractional time part. Should start with the decimal point. Uses 6 decimal places by default.

     # File lib/sequel/dataset/sql.rb
1231 def format_timestamp_usec(usec, ts=timestamp_precision)
1232   # SEQUEL6: Remove
1233   unless ts == 6
1234     usec = usec/(10 ** (6 - ts))
1235   end
1236   sprintf(".%0#{ts}d", usec)
1237 end
grouping_element_list_append(sql, columns) click to toggle source

Append literalization of array of grouping elements to SQL string, seperating them with commas.

     # File lib/sequel/dataset/sql.rb
1203 def grouping_element_list_append(sql, columns)
1204   c = false
1205   co = ', '
1206   columns.each do |col|
1207     sql << co if c
1208     if col.is_a?(Array) && col.empty?
1209       sql << '()'
1210     else
1211       literal_append(sql, Array(col))
1212     end
1213     c ||= true
1214   end
1215 end
identifier_append(sql, v) click to toggle source

Append literalization of identifier to SQL string, considering regular strings as SQL identifiers instead of SQL strings.

     # File lib/sequel/dataset/sql.rb
1242 def identifier_append(sql, v)
1243   if v.is_a?(String)
1244     case v
1245     when LiteralString
1246       sql << v
1247     when SQL::Blob
1248       literal_append(sql, v)
1249     else
1250       quote_identifier_append(sql, v)
1251     end
1252   else
1253     literal_append(sql, v)
1254   end
1255 end
identifier_list_append(sql, args) click to toggle source

Append literalization of array of identifiers to SQL string.

     # File lib/sequel/dataset/sql.rb
1258 def identifier_list_append(sql, args)
1259   c = false
1260   comma = ', '
1261   args.each do |a|
1262     sql << comma if c
1263     identifier_append(sql, a)
1264     c ||= true
1265   end
1266 end
input_identifier(v) click to toggle source

Upcase identifiers by default when inputting them into the database.

     # File lib/sequel/dataset/sql.rb
1269 def input_identifier(v)
1270   v.to_s.upcase
1271 end
insert_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1282 def insert_columns_sql(sql)
1283   _insert_columns_sql(sql, opts[:columns])
1284 end
insert_empty_columns_values() click to toggle source

The columns and values to use for an empty insert if the database doesn't support INSERT with DEFAULT VALUES.

     # File lib/sequel/dataset/sql.rb
1296 def insert_empty_columns_values
1297   [[columns.last], [DEFAULT]]
1298 end
insert_insert_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1300 def insert_insert_sql(sql)
1301   sql << "INSERT"
1302 end
insert_into_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1273 def insert_into_sql(sql)
1274   sql << " INTO "
1275   if (f = @opts[:from]) && f.length == 1
1276     identifier_append(sql, unaliased_identifier(f.first))
1277   else
1278     source_list_append(sql, f)
1279   end
1280 end
insert_returning_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1327 def insert_returning_sql(sql)
1328   if opts.has_key?(:returning)
1329     sql << " RETURNING "
1330     column_list_append(sql, Array(opts[:returning]))
1331   end
1332 end
insert_values_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1304 def insert_values_sql(sql)
1305   _insert_values_sql(sql, opts[:values])
1306 end
insert_with_sql(sql)
Alias for: select_with_sql
join_type_sql(join_type) click to toggle source

SQL fragment specifying a JOIN type, converts underscores to spaces and upcases.

     # File lib/sequel/dataset/sql.rb
1338 def join_type_sql(join_type)
1339   "#{join_type.to_s.gsub('_', ' ').upcase} JOIN"
1340 end
join_using_clause_using_sql_append(sql, using_columns) click to toggle source

Append USING clause for JOIN USING

     # File lib/sequel/dataset/sql.rb
1343 def join_using_clause_using_sql_append(sql, using_columns)
1344   sql << ' USING ('
1345   column_list_append(sql, using_columns)
1346   sql << ')'
1347 end
literal_array_append(sql, v) click to toggle source

Append a literalization of the array to SQL string. Treats as an expression if an array of all two pairs, or as a SQL array otherwise.

     # File lib/sequel/dataset/sql.rb
1351 def literal_array_append(sql, v)
1352   if Sequel.condition_specifier?(v)
1353     literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1354   else
1355     array_sql_append(sql, v)
1356   end
1357 end
literal_big_decimal(v) click to toggle source

SQL fragment for BigDecimal

     # File lib/sequel/dataset/sql.rb
1360 def literal_big_decimal(v)
1361   d = v.to_s("F")
1362   v.nan? || v.infinite? ?  "'#{d}'" : d
1363 end
literal_blob_append(sql, v) click to toggle source

Append literalization of SQL::Blob to SQL string.

     # File lib/sequel/dataset/sql.rb
1366 def literal_blob_append(sql, v)
1367   literal_string_append(sql, v)
1368 end
literal_dataset_append(sql, v) click to toggle source

Append literalization of dataset to SQL string. Does a subselect inside parantheses.

     # File lib/sequel/dataset/sql.rb
1371 def literal_dataset_append(sql, v)
1372   sql << 'LATERAL ' if v.opts[:lateral]
1373   sql << '('
1374   subselect_sql_append(sql, v)
1375   sql << ')'
1376 end
literal_date(v) click to toggle source

SQL fragment for Date, using the ISO8601 format.

     # File lib/sequel/dataset/sql.rb
1379 def literal_date(v)
1380   v.strftime("'%Y-%m-%d'")
1381 end
literal_date_append(sql, v) click to toggle source

Append literalization of date to SQL string.

     # File lib/sequel/dataset/sql.rb
1384 def literal_date_append(sql, v)
1385   sql << literal_date(v)
1386 end
literal_datetime(v) click to toggle source

SQL fragment for DateTime

     # File lib/sequel/dataset/sql.rb
1389 def literal_datetime(v)
1390   format_timestamp(v)
1391 end
literal_datetime_append(sql, v) click to toggle source

Append literalization of DateTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1394 def literal_datetime_append(sql, v)
1395   sql << literal_datetime(v)
1396 end
literal_expression_append(sql, v) click to toggle source

Append literalization of SQL::Expression to SQL string.

     # File lib/sequel/dataset/sql.rb
1399 def literal_expression_append(sql, v)
1400   v.to_s_append(self, sql)
1401 end
literal_false() click to toggle source

SQL fragment for false

     # File lib/sequel/dataset/sql.rb
1404 def literal_false
1405   "'f'"
1406 end
literal_float(v) click to toggle source

SQL fragment for Float

     # File lib/sequel/dataset/sql.rb
1409 def literal_float(v)
1410   v.to_s
1411 end
literal_hash_append(sql, v) click to toggle source

Append literalization of Hash to SQL string, treating hash as a boolean expression.

     # File lib/sequel/dataset/sql.rb
1414 def literal_hash_append(sql, v)
1415   literal_expression_append(sql, SQL::BooleanExpression.from_value_pairs(v))
1416 end
literal_integer(v) click to toggle source

SQL fragment for Integer

     # File lib/sequel/dataset/sql.rb
1419 def literal_integer(v)
1420   v.to_s
1421 end
literal_nil() click to toggle source

SQL fragment for nil

     # File lib/sequel/dataset/sql.rb
1424 def literal_nil
1425   "NULL"
1426 end
literal_other_append(sql, v) click to toggle source

Append a literalization of the object to the given SQL string. Calls sql_literal_append if object responds to it, otherwise calls sql_literal if object responds to it, otherwise raises an error. If a database specific type is allowed, this should be overriden in a subclass.

     # File lib/sequel/dataset/sql.rb
1432 def literal_other_append(sql, v)
1433   # We can't be sure if v will always literalize to the same SQL, so
1434   # don't cache SQL for a dataset that uses this.
1435   disable_sql_caching!
1436 
1437   if v.respond_to?(:sql_literal_append)
1438     v.sql_literal_append(self, sql)
1439   elsif v.respond_to?(:sql_literal)
1440     sql << v.sql_literal(self)
1441   else
1442     raise Error, "can't express #{v.inspect} as a SQL literal"
1443   end
1444 end
literal_sqltime(v) click to toggle source

SQL fragment for Sequel::SQLTime, containing just the time part

     # File lib/sequel/dataset/sql.rb
1447 def literal_sqltime(v)
1448   v.strftime(default_time_format)
1449 end
literal_sqltime_append(sql, v) click to toggle source

Append literalization of Sequel::SQLTime to SQL string.

     # File lib/sequel/dataset/sql.rb
1452 def literal_sqltime_append(sql, v)
1453   sql << literal_sqltime(v)
1454 end
literal_string_append(sql, v) click to toggle source

Append literalization of string to SQL string.

     # File lib/sequel/dataset/sql.rb
1457 def literal_string_append(sql, v)
1458   sql << "'" << v.gsub("'", "''") << "'"
1459 end
literal_symbol_append(sql, v) click to toggle source

Append literalization of symbol to SQL string.

     # File lib/sequel/dataset/sql.rb
1462 def literal_symbol_append(sql, v)
1463   c_table, column, c_alias = split_symbol(v)
1464   if c_table
1465     quote_identifier_append(sql, c_table)
1466     sql << '.'
1467   end
1468   quote_identifier_append(sql, column)
1469   as_sql_append(sql, c_alias) if c_alias
1470 end
literal_time(v) click to toggle source

SQL fragment for Time

     # File lib/sequel/dataset/sql.rb
1473 def literal_time(v)
1474   format_timestamp(v)
1475 end
literal_time_append(sql, v) click to toggle source

Append literalization of Time to SQL string.

     # File lib/sequel/dataset/sql.rb
1478 def literal_time_append(sql, v)
1479   sql << literal_time(v)
1480 end
literal_true() click to toggle source

SQL fragment for true

     # File lib/sequel/dataset/sql.rb
1483 def literal_true
1484   "'t'"
1485 end
multi_insert_sql_strategy() click to toggle source

What strategy to use for import/multi_insert. While SQL-92 defaults to allowing multiple rows in a VALUES clause, there are enough databases that don't allow that that it can't be the default. Use separate queries by default, which works everywhere.

     # File lib/sequel/dataset/sql.rb
1491 def multi_insert_sql_strategy
1492   :separate
1493 end
native_function_name(emulated_function) click to toggle source

Get the native function name given the emulated function name.

     # File lib/sequel/dataset/sql.rb
1497 def native_function_name(emulated_function)
1498   emulated_function
1499 end
qualified_column_name(column, table) click to toggle source

Returns a qualified column name (including a table name) if the column name isn't already qualified.

     # File lib/sequel/dataset/sql.rb
1503 def qualified_column_name(column, table)
1504   if column.is_a?(Symbol)
1505     c_table, column, _ = split_symbol(column)
1506     unless c_table
1507       case table
1508       when Symbol
1509         schema, table, t_alias = split_symbol(table)
1510         t_alias ||= Sequel::SQL::QualifiedIdentifier.new(schema, table) if schema
1511       when Sequel::SQL::AliasedExpression
1512         t_alias = table.alias
1513       end
1514       c_table = t_alias || table
1515     end
1516     ::Sequel::SQL::QualifiedIdentifier.new(c_table, column)
1517   else
1518     column
1519   end
1520 end
qualified_expression(e, table) click to toggle source

Qualify the given expression to the given table.

     # File lib/sequel/dataset/sql.rb
1523 def qualified_expression(e, table)
1524   Qualifier.new(table).transform(e)
1525 end
select_columns_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1527 def select_columns_sql(sql)
1528   sql << ' '
1529   column_list_append(sql, @opts[:select])
1530 end
select_compounds_sql(sql) click to toggle source

Modify the sql to add a dataset to the via an EXCEPT, INTERSECT, or UNION clause. This uses a subselect for the compound datasets used, because using parantheses doesn't work on all databases.

     # File lib/sequel/dataset/sql.rb
1546 def select_compounds_sql(sql)
1547   return unless c = @opts[:compounds]
1548   c.each do |type, dataset, all|
1549     sql << ' ' << type.to_s.upcase
1550     sql << ' ALL' if all
1551     sql << ' '
1552     compound_dataset_sql_append(sql, dataset)
1553   end
1554 end
select_distinct_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1532 def select_distinct_sql(sql)
1533   if distinct = @opts[:distinct]
1534     sql << " DISTINCT"
1535     unless distinct.empty?
1536       sql << " ON ("
1537       expression_list_append(sql, distinct)
1538       sql << ')'
1539     end
1540   end
1541 end
select_from_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1556 def select_from_sql(sql)
1557   if f = @opts[:from]
1558     sql << ' FROM '
1559     source_list_append(sql, f)
1560   elsif f = empty_from_sql
1561     sql << f
1562   end
1563 end
select_group_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1565 def select_group_sql(sql)
1566   if group = @opts[:group]
1567     sql << " GROUP BY "
1568     if go = @opts[:group_options]
1569       if go == :"grouping sets"
1570         sql << go.to_s.upcase << '('
1571         grouping_element_list_append(sql, group)
1572         sql << ')'
1573       elsif uses_with_rollup?
1574         expression_list_append(sql, group)
1575         sql << " WITH " << go.to_s.upcase
1576       else
1577         sql << go.to_s.upcase << '('
1578         expression_list_append(sql, group)
1579         sql << ')'
1580       end
1581     else
1582       expression_list_append(sql, group)
1583     end
1584   end
1585 end
select_having_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1587 def select_having_sql(sql)
1588   if having = @opts[:having]
1589     sql << " HAVING "
1590     literal_append(sql, having)
1591   end
1592 end
select_join_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1594 def select_join_sql(sql)
1595   if js = @opts[:join]
1596     js.each{|j| literal_append(sql, j)}
1597   end
1598 end
select_limit_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1600 def select_limit_sql(sql)
1601   if l = @opts[:limit]
1602     sql << " LIMIT "
1603     literal_append(sql, l)
1604     if o = @opts[:offset]
1605       sql << " OFFSET "
1606       literal_append(sql, o)
1607     end
1608   elsif @opts[:offset]
1609     select_only_offset_sql(sql)
1610   end
1611 end
select_lock_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1613 def select_lock_sql(sql)
1614   case l = @opts[:lock]
1615   when :update
1616     sql << ' FOR UPDATE'
1617   when String
1618     sql << ' ' << l
1619   end
1620 end
select_only_offset_sql(sql) click to toggle source

Used only if there is an offset and no limit, making it easier to override in the adapter, as many databases do not support just a plain offset with no limit.

     # File lib/sequel/dataset/sql.rb
1625 def select_only_offset_sql(sql)
1626   sql << " OFFSET "
1627   literal_append(sql, @opts[:offset])
1628 end
select_order_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1630 def select_order_sql(sql)
1631   if o = @opts[:order]
1632     sql << " ORDER BY "
1633     expression_list_append(sql, o)
1634   end
1635 end
select_select_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1639 def select_select_sql(sql)
1640   sql << 'SELECT'
1641 end
select_where_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1643 def select_where_sql(sql)
1644   if w = @opts[:where]
1645     sql << " WHERE "
1646     literal_append(sql, w)
1647   end
1648 end
select_window_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1652 def select_window_sql(sql)
1653   if ws = @opts[:window]
1654     sql << " WINDOW "
1655     c = false
1656     co = ', '
1657     as = ' AS '
1658     ws.map do |name, window|
1659       sql << co if c
1660       literal_append(sql, name)
1661       sql << as
1662       literal_append(sql, window)
1663       c ||= true
1664     end
1665   end
1666 end
select_with_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1668 def select_with_sql(sql)
1669   return unless supports_cte?
1670   ctes = opts[:with]
1671   return if !ctes || ctes.empty?
1672   sql << select_with_sql_base
1673   c = false
1674   comma = ', '
1675   ctes.each do |cte|
1676     sql << comma if c
1677     select_with_sql_cte(sql, cte)
1678     c ||= true
1679   end
1680   sql << ' '
1681 end
select_with_sql_base() click to toggle source
     # File lib/sequel/dataset/sql.rb
1686 def select_with_sql_base
1687   "WITH "
1688 end
select_with_sql_cte(sql, cte) click to toggle source
     # File lib/sequel/dataset/sql.rb
1690 def select_with_sql_cte(sql, cte)
1691   select_with_sql_prefix(sql, cte)
1692   literal_dataset_append(sql, cte[:dataset])
1693 end
select_with_sql_prefix(sql, w) click to toggle source
     # File lib/sequel/dataset/sql.rb
1695 def select_with_sql_prefix(sql, w)
1696   quote_identifier_append(sql, w[:name])
1697   if args = w[:args]
1698    sql << '('
1699    identifier_list_append(sql, args)
1700    sql << ')'
1701   end
1702   sql << ' AS '
1703 
1704   case w[:materialized]
1705   when true
1706     sql << "MATERIALIZED "
1707   when false
1708     sql << "NOT MATERIALIZED "
1709   end
1710 end
skip_symbol_cache?() click to toggle source

Whether the symbol cache should be skipped when literalizing the dataset

     # File lib/sequel/dataset/sql.rb
1713 def skip_symbol_cache?
1714   @opts[:skip_symbol_cache]
1715 end
source_list_append(sql, sources) click to toggle source

Append literalization of array of sources/tables to SQL string, raising an Error if there are no sources.

     # File lib/sequel/dataset/sql.rb
1719 def source_list_append(sql, sources)
1720   raise(Error, 'No source specified for query') if sources.nil? || sources == []
1721   identifier_list_append(sql, sources)
1722 end
split_symbol(sym) click to toggle source

Delegate to Sequel.split_symbol.

     # File lib/sequel/dataset/sql.rb
1725 def split_symbol(sym)
1726   Sequel.split_symbol(sym)
1727 end
sql_string_origin() click to toggle source

The string that is appended to to create the SQL query, the empty string by default.

     # File lib/sequel/dataset/sql.rb
1731 def sql_string_origin
1732   String.new
1733 end
sqltime_precision() click to toggle source

The precision to use for SQLTime instances (time column values without dates). Defaults to timestamp_precision.

     # File lib/sequel/dataset/sql.rb
1737 def sqltime_precision
1738   timestamp_precision
1739 end
static_sql(sql) click to toggle source

SQL to use if this dataset uses static SQL. Since static SQL can be a PlaceholderLiteralString in addition to a String, we literalize nonstrings. If there is an append_sql for this dataset, append to that SQL instead of returning the value.

     # File lib/sequel/dataset/sql.rb
1745 def static_sql(sql)
1746   if append_sql = @opts[:append_sql]
1747     if sql.is_a?(String)
1748       append_sql << sql
1749     else
1750       literal_append(append_sql, sql)
1751     end
1752   else
1753     if sql.is_a?(String)
1754       sql
1755     else
1756       literal(sql)
1757     end
1758   end
1759 end
subselect_sql_append(sql, ds) click to toggle source

Append literalization of the subselect to SQL string.

     # File lib/sequel/dataset/sql.rb
1762 def subselect_sql_append(sql, ds)
1763   sds = subselect_sql_dataset(sql, ds)
1764   subselect_sql_append_sql(sql, sds)
1765   unless sds.send(:cache_sql?)
1766     # If subquery dataset does not allow caching SQL,
1767     # then this dataset should not allow caching SQL.
1768     disable_sql_caching!
1769   end
1770 end
subselect_sql_append_sql(sql, ds) click to toggle source
     # File lib/sequel/dataset/sql.rb
1776 def subselect_sql_append_sql(sql, ds)
1777   ds.sql
1778 end
subselect_sql_dataset(sql, ds) click to toggle source
     # File lib/sequel/dataset/sql.rb
1772 def subselect_sql_dataset(sql, ds)
1773   ds.clone(:append_sql=>sql)
1774 end
timestamp_precision() click to toggle source

The number of decimal digits of precision to use in timestamps.

     # File lib/sequel/dataset/sql.rb
1781 def timestamp_precision
1782   supports_timestamp_usecs? ? 6 : 0
1783 end
update_order_sql(sql)
Alias for: select_order_sql
update_returning_sql(sql)
update_set_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1791 def update_set_sql(sql)
1792   sql << ' SET '
1793   values = @opts[:values]
1794   if values.is_a?(Hash)
1795     update_sql_values_hash(sql, values)
1796   else
1797     sql << values
1798   end
1799 end
update_sql_values_hash(sql, values) click to toggle source
     # File lib/sequel/dataset/sql.rb
1801 def update_sql_values_hash(sql, values)
1802   c = false
1803   eq = ' = '
1804   values.each do |k, v|
1805     sql << ', ' if c
1806     if k.is_a?(String) && !k.is_a?(LiteralString)
1807       quote_identifier_append(sql, k)
1808     else
1809       literal_append(sql, k)
1810     end
1811     sql << eq
1812     literal_append(sql, v)
1813     c ||= true
1814   end
1815 end
update_table_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1785 def update_table_sql(sql)
1786   sql << ' '
1787   source_list_append(sql, @opts[:from])
1788   select_join_sql(sql) if supports_modifying_joins?
1789 end
update_update_sql(sql) click to toggle source
     # File lib/sequel/dataset/sql.rb
1817 def update_update_sql(sql)
1818   sql << 'UPDATE'
1819 end
update_where_sql(sql)
Alias for: select_where_sql
update_with_sql(sql)
Alias for: select_with_sql
window_frame_boundary_sql_append(sql, boundary, direction) click to toggle source
     # File lib/sequel/dataset/sql.rb
1821 def window_frame_boundary_sql_append(sql, boundary, direction)
1822   case boundary
1823   when :current
1824    sql << "CURRENT ROW"
1825   when :preceding
1826     sql << "UNBOUNDED PRECEDING"
1827   when :following
1828     sql << "UNBOUNDED FOLLOWING"
1829   else
1830     if boundary.is_a?(Array)
1831       offset, direction = boundary
1832       unless boundary.length == 2 && (direction == :preceding || direction == :following)
1833         raise Error, "invalid window :frame boundary (:start or :end) option: #{boundary.inspect}"
1834       end
1835     else
1836       offset = boundary
1837     end
1838 
1839     case offset
1840     when Numeric, String, SQL::Cast
1841       # nothing
1842     else
1843       raise Error, "invalid window :frame boundary (:start or :end) option: #{boundary.inspect}"
1844     end
1845 
1846     literal_append(sql, offset)
1847     sql << (direction == :preceding ? " PRECEDING" : " FOLLOWING")
1848   end
1849 end