Class Sequel::Dataset
In: lib/sequel/extensions/split_array_nil.rb
lib/sequel/extensions/round_timestamps.rb
lib/sequel/extensions/query.rb
lib/sequel/extensions/pagination.rb
lib/sequel/extensions/null_dataset.rb
lib/sequel/extensions/dataset_source_alias.rb
lib/sequel/dataset/sql.rb
lib/sequel/dataset/query.rb
lib/sequel/dataset/prepared_statements.rb
lib/sequel/dataset/placeholder_literalizer.rb
lib/sequel/dataset/mutation.rb
lib/sequel/dataset/misc.rb
lib/sequel/dataset/graph.rb
lib/sequel/dataset/features.rb
lib/sequel/dataset/actions.rb
lib/sequel/dataset.rb
lib/sequel/adapters/utils/stored_procedures.rb
lib/sequel/adapters/utils/replace.rb
lib/sequel/adapters/swift.rb
lib/sequel/adapters/sqlite.rb
lib/sequel/adapters/sqlanywhere.rb
lib/sequel/adapters/mysql.rb
Parent: Object

Dataset class for MySQL datasets accessed via the native driver.

Methods

<<   ==   []   _import   _select_map_multiple   _select_map_single   add_graph_aliases   aliased_expression_sql_append   all   and   array_sql_append   avg   bind   boolean_constant_sql_append   call   call   case_expression_sql_append   cast_sql_append   clause_methods   clone   column_all_sql_append   columns   columns!   complex_expression_sql_append   compound_clone   compound_from_self   constant_sql_append   count   current_datetime   def_mutation_method   def_sql_method   delayed_evaluation_sql_append   delete   distinct   dup   each   each_server   empty?   eql?   escape_like   except   exclude   exclude_having   exclude_where   exists   extension   extension!   fetch_rows   fetch_rows   fetch_rows   fetch_rows   filter   first   first!   first_source   first_source_alias   first_source_table   for_update   freeze   from   from_self   from_self!   frozen?   function_sql_append   get   graph   graph   grep   group   group_and_count   group_by   group_cube   group_rollup   hash   having   identifier_input_method   identifier_input_method=   identifier_output_method   identifier_output_method=   import   insert   insert_sql   inspect   intersect   interval   invert   join   join_clause_sql_append   join_on_clause_sql_append   join_table   join_using_clause_sql_append   joined_dataset?   last   lateral   limit   literal_append   lock_style   map   max   min   multi_insert   multi_insert_sql   naked   naked!   negative_boolean_constant_sql_append   new   offset   options_overlap   or   order   order_append   order_by   order_more   order_prepend   ordered_expression_sql_append   paged_each   placeholder_literal_string_sql_append   prepare   prepare   provides_accurate_rows_matched?   qualified_identifier_sql_append   qualify   quote_identifier_append   quote_identifiers=   quote_identifiers?   quote_schema_table_append   quoted_identifier_append   range   recursive_cte_requires_column_aliases?   register_extension   requires_placeholder_type_specifiers?   requires_sql_standard_datetimes?   returning   reverse   reverse_order   row_number_column   row_proc=   schema_and_table   select   select_all   select_append   select_group   select_hash   select_hash_groups   select_map   select_more   select_order_map   server   server?   set_graph_aliases   simple_select_all?   single_record   single_value   split_alias   split_multiple_result_sets   split_qualifiers   sql   subscript_sql_append   sum   supports_cte?   supports_cte_in_subqueries?   supports_derived_column_lists?   supports_distinct_on?   supports_group_cube?   supports_group_rollup?   supports_insert_select?   supports_intersect_except?   supports_intersect_except_all?   supports_is_true?   supports_join_using?   supports_lateral_subqueries?   supports_limits_in_correlated_subqueries?   supports_modifying_joins?   supports_multiple_column_in?   supports_offsets_in_correlated_subqueries?   supports_ordered_distinct_on?   supports_regexp?   supports_replace?   supports_returning?   supports_select_all_and_column?   supports_timestamp_timezones?   supports_timestamp_usecs?   supports_where_true?   supports_window_functions?   to_hash   to_hash_groups   to_prepared_statement   truncate   truncate_sql   unbind   unfiltered   ungraphed   ungrouped   union   unlimited   unordered   unqualified_column_for   unused_table_alias   update   update_sql   where   window_sql_append   with   with_recursive   with_sql   with_sql_all   with_sql_delete   with_sql_each   with_sql_first   with_sql_insert   with_sql_single_value   with_sql_update  

Included Modules

3 - User Methods relating to SQL Creation

These are methods you can call to see what SQL will be generated by the dataset.

Public Instance methods

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))

[Source]

    # File lib/sequel/dataset/sql.rb, line 12
12:     def exists
13:       SQL::PlaceholderLiteralString.new(EXISTS, [self], true)
14:     end

Returns an INSERT SQL query string. See insert.

  DB[:items].insert_sql(:a=>1)
  # => "INSERT INTO items (a) VALUES (1)"

[Source]

    # File lib/sequel/dataset/sql.rb, line 20
20:     def insert_sql(*values)
21:       return static_sql(@opts[:sql]) if @opts[:sql]
22: 
23:       check_modification_allowed!
24: 
25:       columns = []
26: 
27:       case values.size
28:       when 0
29:         return insert_sql({})
30:       when 1
31:         case vals = values.at(0)
32:         when Hash
33:           values = []
34:           vals.each do |k,v| 
35:             columns << k
36:             values << v
37:           end
38:         when Dataset, Array, LiteralString
39:           values = vals
40:         end
41:       when 2
42:         if (v0 = values.at(0)).is_a?(Array) && ((v1 = values.at(1)).is_a?(Array) || v1.is_a?(Dataset) || v1.is_a?(LiteralString))
43:           columns, values = v0, v1
44:           raise(Error, "Different number of values and columns given to insert_sql") if values.is_a?(Array) and columns.length != values.length
45:         end
46:       end
47: 
48:       if values.is_a?(Array) && values.empty? && !insert_supports_empty_values? 
49:         columns = [columns().last]
50:         values = [DEFAULT]
51:       end
52:       clone(:columns=>columns, :values=>values).send(:_insert_sql)
53:     end

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

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 58
 58:     def literal_append(sql, v)
 59:       case v
 60:       when Symbol
 61:         if skip_symbol_cache?
 62:           literal_symbol_append(sql, v)
 63:         else 
 64:           unless l = db.literal_symbol(v)
 65:             l = ''
 66:             literal_symbol_append(l, v)
 67:             db.literal_symbol_set(v, l)
 68:           end
 69:           sql << l
 70:         end
 71:       when String
 72:         case v
 73:         when LiteralString
 74:           sql << v
 75:         when SQL::Blob
 76:           literal_blob_append(sql, v)
 77:         else
 78:           literal_string_append(sql, v)
 79:         end
 80:       when Integer
 81:         sql << literal_integer(v)
 82:       when Hash
 83:         literal_hash_append(sql, v)
 84:       when SQL::Expression
 85:         literal_expression_append(sql, v)
 86:       when Float
 87:         sql << literal_float(v)
 88:       when BigDecimal
 89:         sql << literal_big_decimal(v)
 90:       when NilClass
 91:         sql << literal_nil
 92:       when TrueClass
 93:         sql << literal_true
 94:       when FalseClass
 95:         sql << literal_false
 96:       when Array
 97:         literal_array_append(sql, v)
 98:       when Time
 99:         v.is_a?(SQLTime) ? literal_sqltime_append(sql, v) : literal_time_append(sql, v)
100:       when DateTime
101:         literal_datetime_append(sql, v)
102:       when Date
103:         sql << literal_date(v)
104:       when Dataset
105:         literal_dataset_append(sql, v)
106:       else
107:         literal_other_append(sql, v)
108:       end
109:     end

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.

This method should be overridden by descendants if the support inserting multiple records in a single SQL statement.

[Source]

     # File lib/sequel/dataset/sql.rb, line 117
117:     def multi_insert_sql(columns, values)
118:       case multi_insert_sql_strategy
119:       when :values
120:         sql = LiteralString.new('VALUES ')
121:         expression_list_append(sql, values.map{|r| Array(r)})
122:         [insert_sql(columns, sql)]
123:       when :union
124:         c = false
125:         sql = LiteralString.new('')
126:         u = UNION_ALL_SELECT
127:         f = empty_from_sql
128:         values.each do |v|
129:           if c
130:             sql << u
131:           else
132:             sql << SELECT << SPACE
133:             c = true
134:           end
135:           expression_list_append(sql, v)
136:           sql << f if f
137:         end
138:         [insert_sql(columns, sql)]
139:       else
140:         values.map{|r| insert_sql(columns, r)}
141:       end
142:     end

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 145
145:     def sql
146:       select_sql
147:     end

Returns a TRUNCATE SQL query string. See truncate

  DB[:items].truncate_sql # => 'TRUNCATE items'

[Source]

     # File lib/sequel/dataset/sql.rb, line 152
152:     def truncate_sql
153:       if opts[:sql]
154:         static_sql(opts[:sql])
155:       else
156:         check_truncation_allowed!
157:         raise(InvalidOperation, "Can't truncate filtered datasets") if opts[:where] || opts[:having]
158:         t = ''
159:         source_list_append(t, opts[:from])
160:         _truncate_sql(t)
161:       end
162:     end

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.

[Source]

     # File lib/sequel/dataset/sql.rb, line 171
171:     def update_sql(values = OPTS)
172:       return static_sql(opts[:sql]) if opts[:sql]
173:       check_modification_allowed!
174:       clone(:values=>values).send(:_update_sql)
175:     end

9 - Internal Methods relating to SQL Creation

These methods, while public, are not designed to be used directly by the end user.

Constants

EMULATED_FUNCTION_MAP = {}   Map of emulated function names to native function names.
WILDCARD = LiteralString.new('*').freeze
ALL = ' ALL'.freeze
AND_SEPARATOR = " AND ".freeze
APOS = "'".freeze
APOS_RE = /'/.freeze
ARRAY_EMPTY = '(NULL)'.freeze
AS = ' AS '.freeze
ASC = ' ASC'.freeze
BACKSLASH = "\\".freeze
BITCOMP_CLOSE = ") - 1)".freeze
BITCOMP_OPEN = "((0 - ".freeze
BITWISE_METHOD_MAP = {:& =>:BITAND, :| => :BITOR, :^ => :BITXOR}
BOOL_FALSE = "'f'".freeze
BOOL_TRUE = "'t'".freeze
BRACKET_CLOSE = ']'.freeze
BRACKET_OPEN = '['.freeze
CASE_ELSE = " ELSE ".freeze
CASE_END = " END)".freeze
CASE_OPEN = '(CASE'.freeze
CASE_THEN = " THEN ".freeze
CASE_WHEN = " WHEN ".freeze
CAST_OPEN = 'CAST('.freeze
COLON = ':'.freeze
COLUMN_REF_RE1 = Sequel::COLUMN_REF_RE1
COLUMN_REF_RE2 = Sequel::COLUMN_REF_RE2
COLUMN_REF_RE3 = Sequel::COLUMN_REF_RE3
COMMA = ', '.freeze
COMMA_SEPARATOR = COMMA
CONDITION_FALSE = '(1 = 0)'.freeze
CONDITION_TRUE = '(1 = 1)'.freeze
COUNT_FROM_SELF_OPTS = [:distinct, :group, :sql, :limit, :offset, :compounds]
COUNT_OF_ALL_AS_COUNT = SQL::Function.new(:count, WILDCARD).as(:count)
DATASET_ALIAS_BASE_NAME = 't'.freeze
DEFAULT = LiteralString.new('DEFAULT').freeze
DEFAULT_VALUES = " DEFAULT VALUES".freeze
DELETE = 'DELETE'.freeze
DESC = ' DESC'.freeze
DISTINCT = " DISTINCT".freeze
DOT = '.'.freeze
DOUBLE_APOS = "''".freeze
DOUBLE_QUOTE = '""'.freeze
EQUAL = ' = '.freeze
ESCAPE = " ESCAPE ".freeze
EXTRACT = 'extract('.freeze
EXISTS = ['EXISTS '.freeze].freeze
FILTER = " FILTER (WHERE ".freeze
FOR_UPDATE = ' FOR UPDATE'.freeze
FORMAT_DATE = "'%Y-%m-%d'".freeze
FORMAT_DATE_STANDARD = "DATE '%Y-%m-%d'".freeze
FORMAT_OFFSET = "%+03i%02i".freeze
FORMAT_TIMESTAMP_RE = /%[Nz]/.freeze
FORMAT_USEC = '%N'.freeze
FRAME_ALL = "ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING".freeze
FRAME_ROWS = "ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW".freeze
FROM = ' FROM '.freeze
FUNCTION_DISTINCT = "DISTINCT ".freeze
GROUP_BY = " GROUP BY ".freeze
HAVING = " HAVING ".freeze
INSERT = "INSERT".freeze
INTO = " INTO ".freeze
IS_LITERALS = {nil=>'NULL'.freeze, true=>'TRUE'.freeze, false=>'FALSE'.freeze}.freeze
IS_OPERATORS = ::Sequel::SQL::ComplexExpression::IS_OPERATORS
LATERAL = 'LATERAL '.freeze
LIKE_OPERATORS = ::Sequel::SQL::ComplexExpression::LIKE_OPERATORS
LIMIT = " LIMIT ".freeze
N_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::N_ARITY_OPERATORS
NOT_SPACE = 'NOT '.freeze
NULL = "NULL".freeze
NULLS_FIRST = " NULLS FIRST".freeze
NULLS_LAST = " NULLS LAST".freeze
OFFSET = " OFFSET ".freeze
ON = ' ON '.freeze
ON_PAREN = " ON (".freeze
ORDER_BY = " ORDER BY ".freeze
ORDER_BY_NS = "ORDER BY ".freeze
OVER = ' OVER '.freeze
PAREN_CLOSE = ')'.freeze
PAREN_OPEN = '('.freeze
PAREN_SPACE_OPEN = ' ('.freeze
PARTITION_BY = "PARTITION BY ".freeze
QUALIFY_KEYS = [:select, :where, :having, :order, :group]
QUESTION_MARK = '?'.freeze
QUESTION_MARK_RE = /\?/.freeze
QUOTE = '"'.freeze
QUOTE_RE = /"/.freeze
RETURNING = " RETURNING ".freeze
SELECT = 'SELECT'.freeze
SET = ' SET '.freeze
SPACE = ' '.freeze
SQL_WITH = "WITH ".freeze
SPACE_WITH = " WITH ".freeze
TILDE = '~'.freeze
TIMESTAMP_FORMAT = "'%Y-%m-%d %H:%M:%S%N%z'".freeze
STANDARD_TIMESTAMP_FORMAT = "TIMESTAMP #{TIMESTAMP_FORMAT}".freeze
TWO_ARITY_OPERATORS = ::Sequel::SQL::ComplexExpression::TWO_ARITY_OPERATORS
REGEXP_OPERATORS = ::Sequel::SQL::ComplexExpression::REGEXP_OPERATORS
UNDERSCORE = '_'.freeze
UPDATE = 'UPDATE'.freeze
USING = ' USING ('.freeze
UNION_ALL_SELECT = ' UNION ALL SELECT '.freeze
VALUES = " VALUES ".freeze
WHERE = " WHERE ".freeze
WITH_ORDINALITY = " WITH ORDINALITY".freeze
WITHIN_GROUP = " WITHIN GROUP (ORDER BY ".freeze
DATETIME_SECFRACTION_ARG = RUBY_VERSION >= '1.9.0' ? 1000000 : 86400000000

Public Class methods

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 184
184:     def self.clause_methods(type, clauses)
185:       clauses.map{|clause| "#{type}_#{clause}_sql""#{type}_#{clause}_sql"}.freeze
186:     end

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.

[Source]

     # File lib/sequel/dataset/sql.rb, line 198
198:     def self.def_sql_method(mod, type, clauses)
199:       priv = type == :update || type == :insert
200: 
201:       lines = []
202:       lines << 'private' if priv
203:       lines << "def #{'_' if priv}#{type}_sql"
204:       lines << 'if sql = opts[:sql]; return static_sql(sql) end' unless priv
205:       lines << 'check_modification_allowed!' if type == :delete
206:       lines << 'sql = @opts[:append_sql] || sql_string_origin'
207: 
208:       if clauses.all?{|c| c.is_a?(Array)}
209:         clauses.each do |i, cs|
210:           lines << i
211:           lines.concat(clause_methods(type, cs).map{|x| "#{x}(sql)"}) 
212:         end 
213:         lines << 'end'
214:       else
215:         lines.concat(clause_methods(type, clauses).map{|x| "#{x}(sql)"})
216:       end
217: 
218:       lines << 'sql'
219:       lines << 'end'
220: 
221:       mod.class_eval lines.join("\n"), __FILE__, __LINE__
222:     end

Public Instance methods

Append literalization of aliased expression to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 351
351:     def aliased_expression_sql_append(sql, ae)
352:       literal_append(sql, ae.expression)
353:       as_sql_append(sql, ae.alias, ae.columns)
354:     end

Append literalization of array to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 357
357:     def array_sql_append(sql, a)
358:       if a.empty?
359:         sql << ARRAY_EMPTY
360:       else
361:         sql << PAREN_OPEN
362:         expression_list_append(sql, a)
363:         sql << PAREN_CLOSE
364:       end
365:     end

Append literalization of boolean constant to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 368
368:     def boolean_constant_sql_append(sql, constant)
369:       if (constant == true || constant == false) && !supports_where_true?
370:         sql << (constant == true ? CONDITION_TRUE : CONDITION_FALSE)
371:       else
372:         literal_append(sql, constant)
373:       end
374:     end

Append literalization of case expression to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 377
377:     def case_expression_sql_append(sql, ce)
378:       sql << CASE_OPEN
379:       if ce.expression?
380:         sql << SPACE
381:         literal_append(sql, ce.expression)
382:       end
383:       w = CASE_WHEN
384:       t = CASE_THEN
385:       ce.conditions.each do |c,r|
386:         sql << w
387:         literal_append(sql, c)
388:         sql << t
389:         literal_append(sql, r)
390:       end
391:       sql << CASE_ELSE
392:       literal_append(sql, ce.default)
393:       sql << CASE_END
394:     end

Append literalization of cast expression to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 397
397:     def cast_sql_append(sql, expr, type)
398:       sql << CAST_OPEN
399:       literal_append(sql, expr)
400:       sql << AS << db.cast_type_literal(type).to_s
401:       sql << PAREN_CLOSE
402:     end

Append literalization of column all selection to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 405
405:     def column_all_sql_append(sql, ca)
406:       qualified_identifier_sql_append(sql, ca.table, WILDCARD)
407:     end

Append literalization of complex expression to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 410
410:     def complex_expression_sql_append(sql, op, args)
411:       case op
412:       when *IS_OPERATORS
413:         r = args.at(1)
414:         if r.nil? || supports_is_true?
415:           raise(InvalidOperation, 'Invalid argument used for IS operator') unless val = IS_LITERALS[r]
416:           sql << PAREN_OPEN
417:           literal_append(sql, args.at(0))
418:           sql << SPACE << op.to_s << SPACE
419:           sql << val << PAREN_CLOSE
420:         elsif op == :IS
421:           complex_expression_sql_append(sql, "=""=", args)
422:         else
423:           complex_expression_sql_append(sql, :OR, [SQL::BooleanExpression.new("!=""!=", *args), SQL::BooleanExpression.new(:IS, args.at(0), nil)])
424:         end
425:       when :IN, "NOT IN""NOT IN"
426:         cols = args.at(0)
427:         vals = args.at(1)
428:         col_array = true if cols.is_a?(Array)
429:         if vals.is_a?(Array)
430:           val_array = true
431:           empty_val_array = vals == []
432:         end
433:         if empty_val_array
434:           literal_append(sql, empty_array_value(op, cols))
435:         elsif col_array
436:           if !supports_multiple_column_in?
437:             if val_array
438:               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]})})
439:               literal_append(sql, op == :IN ? expr : ~expr)
440:             else
441:               old_vals = vals
442:               vals = vals.naked if vals.is_a?(Sequel::Dataset)
443:               vals = vals.to_a
444:               val_cols = old_vals.columns
445:               complex_expression_sql_append(sql, op, [cols, vals.map!{|x| x.values_at(*val_cols)}])
446:             end
447:           else
448:             # If the columns and values are both arrays, use array_sql instead of
449:             # literal so that if values is an array of two element arrays, it
450:             # will be treated as a value list instead of a condition specifier.
451:             sql << PAREN_OPEN
452:             literal_append(sql, cols)
453:             sql << SPACE << op.to_s << SPACE
454:             if val_array
455:               array_sql_append(sql, vals)
456:             else
457:               literal_append(sql, vals)
458:             end
459:             sql << PAREN_CLOSE
460:           end
461:         else
462:           sql << PAREN_OPEN
463:           literal_append(sql, cols)
464:           sql << SPACE << op.to_s << SPACE
465:           literal_append(sql, vals)
466:           sql << PAREN_CLOSE
467:         end
468:       when :LIKE, 'NOT LIKE''NOT LIKE'
469:         sql << PAREN_OPEN
470:         literal_append(sql, args.at(0))
471:         sql << SPACE << op.to_s << SPACE
472:         literal_append(sql, args.at(1))
473:         sql << ESCAPE
474:         literal_append(sql, BACKSLASH)
475:         sql << PAREN_CLOSE
476:       when :ILIKE, 'NOT ILIKE''NOT ILIKE'
477:         complex_expression_sql_append(sql, (op == :ILIKE ? :LIKE : "NOT LIKE""NOT LIKE"), args.map{|v| Sequel.function(:UPPER, v)})
478:       when *TWO_ARITY_OPERATORS
479:         if REGEXP_OPERATORS.include?(op) && !supports_regexp?
480:           raise InvalidOperation, "Pattern matching via regular expressions is not supported on #{db.database_type}"
481:         end
482:         sql << PAREN_OPEN
483:         literal_append(sql, args.at(0))
484:         sql << SPACE << op.to_s << SPACE
485:         literal_append(sql, args.at(1))
486:         sql << PAREN_CLOSE
487:       when *N_ARITY_OPERATORS
488:         sql << PAREN_OPEN
489:         c = false
490:         op_str = " #{op} "
491:         args.each do |a|
492:           sql << op_str if c
493:           literal_append(sql, a)
494:           c ||= true
495:         end
496:         sql << PAREN_CLOSE
497:       when :NOT
498:         sql << NOT_SPACE
499:         literal_append(sql, args.at(0))
500:       when :NOOP
501:         literal_append(sql, args.at(0))
502:       when 'B~''B~'
503:         sql << TILDE
504:         literal_append(sql, args.at(0))
505:       when :extract
506:         sql << EXTRACT << args.at(0).to_s << FROM
507:         literal_append(sql, args.at(1))
508:         sql << PAREN_CLOSE
509:       else
510:         raise(InvalidOperation, "invalid operator #{op}")
511:       end
512:     end

Append literalization of constant to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 515
515:     def constant_sql_append(sql, constant)
516:       sql << constant.to_s
517:     end

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 521
521:     def delayed_evaluation_sql_append(sql, delay)
522:       if recorder = @opts[:placeholder_literalizer]
523:         recorder.use(sql, lambda{delay.call(self)}, nil)
524:       else
525:         literal_append(sql, delay.call(self))
526:       end
527:     end

Append literalization of function call to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 530
530:     def function_sql_append(sql, f)
531:       name = f.name
532:       opts = f.opts
533: 
534:       if opts[:emulate]
535:         if emulate_function?(name)
536:           emulate_function_sql_append(sql, f)
537:           return
538:         end
539: 
540:         name = native_function_name(name) 
541:       end
542: 
543:       sql << LATERAL if opts[:lateral]
544: 
545:       case name
546:       when SQL::Identifier
547:         if supports_quoted_function_names? && opts[:quoted] != false
548:           literal_append(sql, name)
549:         else
550:           sql << name.value.to_s
551:         end
552:       when SQL::QualifiedIdentifier
553:         if supports_quoted_function_names? && opts[:quoted] != false
554:           literal_append(sql, name)
555:         else
556:           sql << split_qualifiers(name).join(DOT)
557:         end
558:       else
559:         if supports_quoted_function_names? && opts[:quoted]
560:           quote_identifier_append(sql, name)
561:         else
562:           sql << name.to_s
563:         end
564:       end
565: 
566:       sql << PAREN_OPEN
567:       if opts[:*]
568:         sql << WILDCARD
569:       else
570:         sql << FUNCTION_DISTINCT if opts[:distinct]
571:         expression_list_append(sql, f.args)
572:       end
573:       sql << PAREN_CLOSE
574: 
575:       if group = opts[:within_group]
576:         sql << WITHIN_GROUP
577:         expression_list_append(sql, group)
578:         sql << PAREN_CLOSE
579:       end
580: 
581:       if filter = opts[:filter]
582:         sql << FILTER
583:         literal_append(sql, filter_expr(filter, &opts[:filter_block]))
584:         sql << PAREN_CLOSE
585:       end
586: 
587:       if window = opts[:over]
588:         sql << OVER
589:         window_sql_append(sql, window.opts)
590:       end
591: 
592:       if opts[:with_ordinality]
593:         sql << WITH_ORDINALITY
594:       end
595:     end

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 598
598:     def join_clause_sql_append(sql, jc)
599:       table = jc.table
600:       table_alias = jc.table_alias
601:       table_alias = nil if table == table_alias && !jc.column_aliases
602:       sql << SPACE << join_type_sql(jc.join_type) << SPACE
603:       identifier_append(sql, table)
604:       as_sql_append(sql, table_alias, jc.column_aliases) if table_alias
605:     end

Append literalization of JOIN ON clause to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 608
608:     def join_on_clause_sql_append(sql, jc)
609:       join_clause_sql_append(sql, jc)
610:       sql << ON
611:       literal_append(sql, filter_expr(jc.on))
612:     end

Append literalization of JOIN USING clause to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 615
615:     def join_using_clause_sql_append(sql, jc)
616:       join_clause_sql_append(sql, jc)
617:       sql << USING
618:       column_list_append(sql, jc.using)
619:       sql << PAREN_CLOSE
620:     end

Append literalization of negative boolean constant to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 623
623:     def negative_boolean_constant_sql_append(sql, constant)
624:       sql << NOT_SPACE
625:       boolean_constant_sql_append(sql, constant)
626:     end

Append literalization of ordered expression to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 629
629:     def ordered_expression_sql_append(sql, oe)
630:       literal_append(sql, oe.expression)
631:       sql << (oe.descending ? DESC : ASC)
632:       case oe.nulls
633:       when :first
634:         sql << NULLS_FIRST
635:       when :last
636:         sql << NULLS_LAST
637:       end
638:     end

Append literalization of placeholder literal string to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 641
641:     def placeholder_literal_string_sql_append(sql, pls)
642:       args = pls.args
643:       str = pls.str
644:       sql << PAREN_OPEN if pls.parens
645:       if args.is_a?(Hash)
646:         if args.empty?
647:           sql << str
648:         else
649:           re = /:(#{args.keys.map{|k| Regexp.escape(k.to_s)}.join('|')})\b/
650:           loop do
651:             previous, q, str = str.partition(re)
652:             sql << previous
653:             literal_append(sql, args[($1||q[1..-1].to_s).to_sym]) unless q.empty?
654:             break if str.empty?
655:           end
656:         end
657:       elsif str.is_a?(Array)
658:         len = args.length
659:         str.each_with_index do |s, i|
660:           sql << s
661:           literal_append(sql, args[i]) unless i == len
662:         end
663:         unless str.length == args.length || str.length == args.length + 1
664:           raise Error, "Mismatched number of placeholders (#{str.length}) and placeholder arguments (#{args.length}) when using placeholder array"
665:         end
666:       else
667:         i = -1
668:         match_len = args.length - 1
669:         loop do
670:           previous, q, str = str.partition(QUESTION_MARK)
671:           sql << previous
672:           literal_append(sql, args.at(i+=1)) unless q.empty?
673:           if str.empty?
674:             unless i == match_len
675:               raise Error, "Mismatched number of placeholders (#{i+1}) and placeholder arguments (#{args.length}) when using placeholder array"
676:             end
677:             break
678:           end
679:         end
680:       end
681:       sql << PAREN_CLOSE if pls.parens
682:     end

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.

[Source]

     # File lib/sequel/dataset/sql.rb, line 687
687:     def qualified_identifier_sql_append(sql, table, column=(c = table.column; table = table.table; c))
688:       identifier_append(sql, table)
689:       sql << DOT
690:       identifier_append(sql, column)
691:     end

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.

[Source]

     # File lib/sequel/dataset/sql.rb, line 697
697:     def quote_identifier_append(sql, name)
698:       if name.is_a?(LiteralString)
699:         sql << name
700:       else
701:         name = name.value if name.is_a?(SQL::Identifier)
702:         name = input_identifier(name)
703:         if quote_identifiers?
704:           quoted_identifier_append(sql, name)
705:         else
706:           sql << name
707:         end
708:       end
709:     end

Append literalization of identifier or unqualified identifier to SQL string.

[Source]

     # File lib/sequel/dataset/sql.rb, line 712
712:     def quote_schema_table_append(sql, table)
713:       schema, table = schema_and_table(table)
714:       if schema
715:         quote_identifier_append(sql, schema)
716:         sql << DOT
717:       end
718:       quote_identifier_append(sql, table)
719:     end

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).

[Source]

     # File lib/sequel/dataset/sql.rb, line 725
725:     def quoted_identifier_append(sql, name)
726:       sql << QUOTE << name.to_s.gsub(QUOTE_RE, DOUBLE_QUOTE) << QUOTE
727:     end

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).

[Source]

     # File lib/sequel/dataset/sql.rb, line 736
736:     def schema_and_table(table_name, sch=nil)
737:       sch = sch.to_s if sch
738:       case table_name
739:       when Symbol
740:         s, t, _ = split_symbol(table_name)
741:         [s||sch, t]
742:       when SQL::QualifiedIdentifier
743:         [table_name.table.to_s, table_name.column.to_s]
744:       when SQL::Identifier
745:         [sch, table_name.value.to_s]
746:       when String
747:         [sch, table_name]
748:       else
749:         raise Error, 'table_name should be a Symbol, SQL::QualifiedIdentifier, SQL::Identifier, or String'
750:       end
751:     end

Splits table_name into an array of strings.

  ds.split_qualifiers(:s) # ['s']
  ds.split_qualifiers(:t__s) # ['t', 's']
  ds.split_qualifiers(Sequel.qualify(:d, :t__s)) # ['d', 't', 's']
  ds.split_qualifiers(Sequel.qualify(:h__d, :t__s)) # ['h', 'd', 't', 's']

[Source]

     # File lib/sequel/dataset/sql.rb, line 759
759:     def split_qualifiers(table_name, *args)
760:       case table_name
761:       when SQL::QualifiedIdentifier
762:         split_qualifiers(table_name.table, nil) + split_qualifiers(table_name.column, nil)
763:       else
764:         sch, table = schema_and_table(table_name, *args)
765:         sch ? [sch, table] : [table]
766:       end
767:     end

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 770
770:     def subscript_sql_append(sql, s)
771:       literal_append(sql, s.f)
772:       sql << BRACKET_OPEN
773:       if s.sub.length == 1 && (range = s.sub.first).is_a?(Range)
774:         literal_append(sql, range.begin)
775:         sql << COLON
776:         e = range.end
777:         e -= 1 if range.exclude_end? && e.is_a?(Integer)
778:         literal_append(sql, e)
779:       else
780:         expression_list_append(sql, s.sub)
781:       end
782:       sql << BRACKET_CLOSE
783:     end

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 786
786:     def window_sql_append(sql, opts)
787:       raise(Error, 'This dataset does not support window functions') unless supports_window_functions?
788:       sql << PAREN_OPEN
789:       window, part, order, frame = opts.values_at(:window, :partition, :order, :frame)
790:       space = false
791:       space_s = SPACE
792:       if window
793:         literal_append(sql, window)
794:         space = true
795:       end
796:       if part
797:         sql << space_s if space
798:         sql << PARTITION_BY
799:         expression_list_append(sql, Array(part))
800:         space = true
801:       end
802:       if order
803:         sql << space_s if space
804:         sql << ORDER_BY_NS
805:         expression_list_append(sql, Array(order))
806:         space = true
807:       end
808:       case frame
809:         when nil
810:           # nothing
811:         when :all
812:           sql << space_s if space
813:           sql << FRAME_ALL
814:         when :rows
815:           sql << space_s if space
816:           sql << FRAME_ROWS
817:         when String
818:           sql << space_s if space
819:           sql << frame
820:         else
821:           raise Error, "invalid window frame clause, should be :all, :rows, a string, or nil"
822:       end
823:       sql << PAREN_CLOSE
824:     end

Protected Instance methods

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

[Source]

     # File lib/sequel/dataset/sql.rb, line 830
830:     def compound_from_self
831:       (@opts[:sql] || @opts[:limit] || @opts[:order]) ? from_self : self
832:     end

1 - Methods that return modified datasets

These methods all return modified copies of the receiver.

Constants

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).
COLUMN_CHANGE_OPTS = [:select, :sql, :from, :join].freeze   The dataset options that require the removal of cached columns if changed.
NON_SQL_OPTIONS = [:server, :defaults, :overrides, :graph, :eager, :eager_graph, :graph_aliases]   Which options don‘t affect the SQL generation. Used by simple_select_all? to determine if this is a simple SELECT * FROM table.
CONDITIONED_JOIN_TYPES = [:inner, :full_outer, :right_outer, :left_outer, :full, :right, :left]   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.
UNCONDITIONED_JOIN_TYPES = [:natural, :natural_left, :natural_right, :natural_full, :cross]   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.
JOIN_METHODS = (CONDITIONED_JOIN_TYPES + UNCONDITIONED_JOIN_TYPES).map{|x| "#{x}_join".to_sym} + [:join, :join_table]   All methods that return modified datasets with a joined table added.
QUERY_METHODS = (<<-METHS).split.map{|x| x.to_sym} + JOIN_METHODS add_graph_aliases and distinct except exclude exclude_having exclude_where filter for_update from from_self graph grep group group_and_count group_by having intersect invert limit lock_style naked offset or order order_append order_by order_more order_prepend qualify reverse reverse_order select select_all select_append select_group select_more server set_graph_aliases unfiltered ungraphed ungrouped union unlimited unordered where with with_recursive with_sql METHS ).split.map{|x| x.to_sym} + JOIN_METHODS   Methods that return modified datasets

Public Class methods

Register an extension callback for Dataset objects. ext should be the extension name symbol, and mod should either be a Module that the dataset is extended with, or a callable object called with the database object. If mod is not provided, a block can be provided and is treated as the mod object.

If mod is a module, this also registers a Database extension that will extend all of the database‘s datasets.

[Source]

    # File lib/sequel/dataset/query.rb, line 53
53:     def self.register_extension(ext, mod=nil, &block)
54:       if mod
55:         raise(Error, "cannot provide both mod and block to Dataset.register_extension") if block
56:         if mod.is_a?(Module)
57:           block = proc{|ds| ds.extend(mod)}
58:           Sequel::Database.register_extension(ext){|db| db.extend_datasets(mod)}
59:         else
60:           block = mod
61:         end
62:       end
63:       Sequel.synchronize{EXTENSIONS[ext] = block}
64:     end

Public Instance methods

Alias for where.

[Source]

    # File lib/sequel/dataset/query.rb, line 67
67:     def and(*cond, &block)
68:       where(*cond, &block)
69:     end

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.

[Source]

    # File lib/sequel/dataset/query.rb, line 75
75:     def clone(opts = nil)
76:       c = super()
77:       if opts
78:         c.instance_variable_set(:@opts, @opts.merge(opts))
79:         c.instance_variable_set(:@columns, nil) if @columns && !opts.each_key{|o| break if COLUMN_CHANGE_OPTS.include?(o)}
80:       else
81:         c.instance_variable_set(:@opts, @opts.dup)
82:       end
83:       c
84:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 96
 96:     def distinct(*args, &block)
 97:       virtual_row_columns(args, block)
 98:       raise(InvalidOperation, "DISTINCT ON not supported") if !args.empty? && !supports_distinct_on?
 99:       clone(:distinct => args)
100:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 119
119:     def except(dataset, opts=OPTS)
120:       raise(InvalidOperation, "EXCEPT not supported") unless supports_intersect_except?
121:       raise(InvalidOperation, "EXCEPT ALL not supported") if opts[:all] && !supports_intersect_except_all?
122:       compound_clone(:except, dataset, opts)
123:     end

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))

[Source]

     # File lib/sequel/dataset/query.rb, line 133
133:     def exclude(*cond, &block)
134:       _filter_or_exclude(true, :where, *cond, &block)
135:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 141
141:     def exclude_having(*cond, &block)
142:       _filter_or_exclude(true, :having, *cond, &block)
143:     end

Alias for exclude.

[Source]

     # File lib/sequel/dataset/query.rb, line 146
146:     def exclude_where(*cond, &block)
147:       exclude(*cond, &block)
148:     end

Return a clone of the dataset loaded with the extensions, see extension!.

[Source]

     # File lib/sequel/dataset/query.rb, line 151
151:     def extension(*exts)
152:       clone.extension!(*exts)
153:     end

Alias for where.

[Source]

     # File lib/sequel/dataset/query.rb, line 156
156:     def filter(*cond, &block)
157:       where(*cond, &block)
158:     end

Returns a cloned dataset with a :update lock style.

  DB[:table].for_update # SELECT * FROM table FOR UPDATE

[Source]

     # File lib/sequel/dataset/query.rb, line 163
163:     def for_update
164:       lock_style(:update)
165:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 176
176:     def from(*source, &block)
177:       virtual_row_columns(source, block)
178:       table_alias_num = 0
179:       ctes = nil
180:       source.map! do |s|
181:         case s
182:         when Dataset
183:           if hoist_cte?(s)
184:             ctes ||= []
185:             ctes += s.opts[:with]
186:             s = s.clone(:with=>nil)
187:           end
188:           SQL::AliasedExpression.new(s, dataset_alias(table_alias_num+=1))
189:         when Symbol
190:           sch, table, aliaz = split_symbol(s)
191:           if aliaz
192:             s = sch ? SQL::QualifiedIdentifier.new(sch, table) : SQL::Identifier.new(table)
193:             SQL::AliasedExpression.new(s, aliaz.to_sym)
194:           else
195:             s
196:           end
197:         else
198:           s
199:         end
200:       end
201:       o = {:from=>source.empty? ? nil : source}
202:       o[:with] = (opts[:with] || []) + ctes if ctes
203:       o[:num_dataset_sources] = table_alias_num if table_alias_num > 0
204:       clone(o)
205:     end

Returns a dataset selecting from the current dataset. Supplying the :alias option controls the alias of the result.

  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)

[Source]

     # File lib/sequel/dataset/query.rb, line 221
221:     def from_self(opts=OPTS)
222:       fs = {}
223:       @opts.keys.each{|k| fs[k] = nil unless NON_SQL_OPTIONS.include?(k)}
224:       clone(fs).from(opts[:alias] ? as(opts[:alias], opts[:column_aliases]) : self)
225:     end

Match any of the columns to any of the patterns. The terms can be strings (which use LIKE) or regular expressions (which are only supported on MySQL and PostgreSQL). 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 '\'))

[Source]

     # File lib/sequel/dataset/query.rb, line 262
262:     def grep(columns, patterns, opts=OPTS)
263:       if opts[:all_patterns]
264:         conds = Array(patterns).map do |pat|
265:           SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *Array(columns).map{|c| SQL::StringExpression.like(c, pat, opts)})
266:         end
267:         where(SQL::BooleanExpression.new(opts[:all_patterns] ? :AND : :OR, *conds))
268:       else
269:         conds = Array(columns).map do |c|
270:           SQL::BooleanExpression.new(:OR, *Array(patterns).map{|pat| SQL::StringExpression.like(c, pat, opts)})
271:         end
272:         where(SQL::BooleanExpression.new(opts[:all_columns] ? :AND : :OR, *conds))
273:       end
274:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 283
283:     def group(*columns, &block)
284:       virtual_row_columns(columns, block)
285:       clone(:group => (columns.compact.empty? ? nil : columns))
286:     end

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(:first_name___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}, ...]

[Source]

     # File lib/sequel/dataset/query.rb, line 314
314:     def group_and_count(*columns, &block)
315:       select_group(*columns, &block).select_more(COUNT_OF_ALL_AS_COUNT)
316:     end

Alias of group

[Source]

     # File lib/sequel/dataset/query.rb, line 289
289:     def group_by(*columns, &block)
290:       group(*columns, &block)
291:     end

Adds the appropriate CUBE syntax to GROUP BY.

[Source]

     # File lib/sequel/dataset/query.rb, line 319
319:     def group_cube
320:       raise Error, "GROUP BY CUBE not supported on #{db.database_type}" unless supports_group_cube?
321:       clone(:group_options=>:cube)
322:     end

Adds the appropriate ROLLUP syntax to GROUP BY.

[Source]

     # File lib/sequel/dataset/query.rb, line 325
325:     def group_rollup
326:       raise Error, "GROUP BY ROLLUP not supported on #{db.database_type}" unless supports_group_rollup?
327:       clone(:group_options=>:rollup)
328:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 334
334:     def having(*cond, &block)
335:       _filter(:having, *cond, &block)
336:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 355
355:     def intersect(dataset, opts=OPTS)
356:       raise(InvalidOperation, "INTERSECT not supported") unless supports_intersect_except?
357:       raise(InvalidOperation, "INTERSECT ALL not supported") if opts[:all] && !supports_intersect_except_all?
358:       compound_clone(:intersect, dataset, opts)
359:     end

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))

[Source]

     # File lib/sequel/dataset/query.rb, line 369
369:     def invert
370:       having, where = @opts.values_at(:having, :where)
371:       if having.nil? && where.nil?
372:         where(false)
373:       else
374:         o = {}
375:         o[:having] = SQL::BooleanExpression.invert(having) if having
376:         o[:where] = SQL::BooleanExpression.invert(where) if where
377:         clone(o)
378:       end
379:     end

Alias of inner_join

[Source]

     # File lib/sequel/dataset/query.rb, line 382
382:     def join(*args, &block)
383:       inner_join(*args, &block)
384:     end

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.
: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, :b___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)))

[Source]

     # File lib/sequel/dataset/query.rb, line 445
445:     def join_table(type, table, expr=nil, options=OPTS, &block)
446:       if hoist_cte?(table)
447:         s, ds = hoist_cte(table)
448:         return s.join_table(type, ds, expr, options, &block)
449:       end
450: 
451:       using_join = expr.is_a?(Array) && !expr.empty? && expr.all?{|x| x.is_a?(Symbol)}
452:       if using_join && !supports_join_using?
453:         h = {}
454:         expr.each{|e| h[e] = e}
455:         return join_table(type, table, h, options)
456:       end
457: 
458:       table_alias = options[:table_alias]
459:       last_alias = options[:implicit_qualifier]
460:       qualify_type = options[:qualify]
461: 
462:       if table.is_a?(SQL::AliasedExpression)
463:         table_expr = if table_alias
464:           SQL::AliasedExpression.new(table.expression, table_alias, table.columns)
465:         else
466:           table
467:         end
468:         table = table_expr.expression
469:         table_name = table_alias = table_expr.alias
470:       elsif table.is_a?(Dataset)
471:         if table_alias.nil?
472:           table_alias_num = (@opts[:num_dataset_sources] || 0) + 1
473:           table_alias = dataset_alias(table_alias_num)
474:         end
475:         table_name = table_alias
476:         table_expr = SQL::AliasedExpression.new(table, table_alias)
477:       else
478:         table, implicit_table_alias = split_alias(table)
479:         table_alias ||= implicit_table_alias
480:         table_name = table_alias || table
481:         table_expr = table_alias ? SQL::AliasedExpression.new(table, table_alias) : table
482:       end
483: 
484:       join = if expr.nil? and !block
485:         SQL::JoinClause.new(type, table_expr)
486:       elsif using_join
487:         raise(Sequel::Error, "can't use a block if providing an array of symbols as expr") if block
488:         SQL::JoinUsingClause.new(expr, type, table_expr)
489:       else
490:         last_alias ||= @opts[:last_joined_table] || first_source_alias
491:         if Sequel.condition_specifier?(expr)
492:           expr = expr.collect do |k, v|
493:             qualify_type = default_join_table_qualification if qualify_type.nil?
494:             case qualify_type
495:             when false
496:               nil # Do no qualification
497:             when :deep
498:               k = Sequel::Qualifier.new(self, table_name).transform(k)
499:               v = Sequel::Qualifier.new(self, last_alias).transform(v)
500:             else
501:               k = qualified_column_name(k, table_name) if k.is_a?(Symbol)
502:               v = qualified_column_name(v, last_alias) if v.is_a?(Symbol)
503:             end
504:             [k,v]
505:           end
506:           expr = SQL::BooleanExpression.from_value_pairs(expr)
507:         end
508:         if block
509:           expr2 = yield(table_name, last_alias, @opts[:join] || [])
510:           expr = expr ? SQL::BooleanExpression.new(:AND, expr, expr2) : expr2
511:         end
512:         SQL::JoinOnClause.new(expr, type, table_expr)
513:       end
514: 
515:       opts = {:join => (@opts[:join] || []) + [join]}
516:       opts[:last_joined_table] = table_name unless options[:reset_implicit_qualifier] == false
517:       opts[:num_dataset_sources] = table_alias_num if table_alias_num
518:       clone(opts)
519:     end

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(:a__c=>:b__d).lateral)
  # SELECT * FROM a, LATERAL (SELECT * FROM b WHERE (a.c = b.d))

[Source]

     # File lib/sequel/dataset/query.rb, line 541
541:     def lateral
542:       clone(:lateral=>true)
543:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 555
555:     def limit(l, o = (no_offset = true; nil))
556:       return from_self.limit(l, o) if @opts[:sql]
557: 
558:       if l.is_a?(Range)
559:         no_offset = false
560:         o = l.first
561:         l = l.last - l.first + (l.exclude_end? ? 0 : 1)
562:       end
563:       l = l.to_i if l.is_a?(String) && !l.is_a?(LiteralString)
564:       if l.is_a?(Integer)
565:         raise(Error, 'Limits must be greater than or equal to 1') unless l >= 1
566:       end
567: 
568:       ds = clone(:limit=>l)
569:       ds = ds.offset(o) unless no_offset
570:       ds
571:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 582
582:     def lock_style(style)
583:       clone(:lock => style)
584:     end

Returns a cloned dataset without a row_proc.

  ds = DB[:items]
  ds.row_proc = proc{|r| r.invert}
  ds.all # => [{2=>:id}]
  ds.naked.all # => [{:id=>2}]

[Source]

     # File lib/sequel/dataset/query.rb, line 592
592:     def naked
593:       ds = clone
594:       ds.row_proc = nil
595:       ds
596:     end

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 override the offset if you‘ve called offset first.

  DB[:items].offset(10) # SELECT * FROM items OFFSET 10

[Source]

     # File lib/sequel/dataset/query.rb, line 603
603:     def offset(o)
604:       o = o.to_i if o.is_a?(String) && !o.is_a?(LiteralString)
605:       if o.is_a?(Integer)
606:         raise(Error, 'Offsets must be greater than or equal to 0') unless o >= 0
607:       end
608:       clone(:offset => o)
609:     end

Adds an alternate filter to an existing filter using OR. If no filter exists an Error is raised.

  DB[:items].where(:a).or(:b) # SELECT * FROM items WHERE a OR b

[Source]

     # File lib/sequel/dataset/query.rb, line 615
615:     def or(*cond, &block)
616:       cond = cond.first if cond.size == 1
617:       v = @opts[:where]
618:       if v.nil? || (cond.respond_to?(:empty?) && cond.empty? && !block)
619:         clone
620:       else
621:         clone(:where => SQL::BooleanExpression.new(:OR, v, filter_expr(cond, &block)))
622:       end
623:     end

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(: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

[Source]

     # File lib/sequel/dataset/query.rb, line 639
639:     def order(*columns, &block)
640:       virtual_row_columns(columns, block)
641:       clone(:order => (columns.compact.empty?) ? nil : columns)
642:     end

Alias of order_more, for naming consistency with order_prepend.

[Source]

     # File lib/sequel/dataset/query.rb, line 645
645:     def order_append(*columns, &block)
646:       order_more(*columns, &block)
647:     end

Alias of order

[Source]

     # File lib/sequel/dataset/query.rb, line 650
650:     def order_by(*columns, &block)
651:       order(*columns, &block)
652:     end

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_more(:b) # SELECT * FROM items ORDER BY a, b

[Source]

     # File lib/sequel/dataset/query.rb, line 659
659:     def order_more(*columns, &block)
660:       columns = @opts[:order] + columns if @opts[:order]
661:       order(*columns, &block)
662:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 669
669:     def order_prepend(*columns, &block)
670:       ds = order(*columns, &block)
671:       @opts[:order] ? ds.order_more(*@opts[:order]) : ds
672:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 681
681:     def qualify(table=first_source)
682:       o = @opts
683:       return clone if o[:sql]
684:       h = {}
685:       (o.keys & QUALIFY_KEYS).each do |k|
686:         h[k] = qualified_expression(o[k], table)
687:       end
688:       h[:select] = [SQL::ColumnAll.new(table)] if !o[:select] || o[:select].empty?
689:       clone(h)
690:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 700
700:     def returning(*values)
701:       raise Error, "RETURNING is not supported on #{db.database_type}" unless supports_returning?(:insert)
702:       clone(:returning=>values)
703:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 712
712:     def reverse(*order, &block)
713:       virtual_row_columns(order, block)
714:       order(*invert_order(order.empty? ? @opts[:order] : order))
715:     end

Alias of reverse

[Source]

     # File lib/sequel/dataset/query.rb, line 718
718:     def reverse_order(*order, &block)
719:       reverse(*order, &block)
720:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 729
729:     def select(*columns, &block)
730:       virtual_row_columns(columns, block)
731:       clone(:select => columns)
732:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 741
741:     def select_all(*tables)
742:       if tables.empty?
743:         clone(:select => nil)
744:       else
745:         select(*tables.map{|t| i, a = split_alias(t); a || i}.map{|t| SQL::ColumnAll.new(t)})
746:       end
747:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 756
756:     def select_append(*columns, &block)
757:       cur_sel = @opts[:select]
758:       if !cur_sel || cur_sel.empty?
759:         unless supports_select_all_and_column?
760:           return select_all(*(Array(@opts[:from]) + Array(@opts[:join]))).select_more(*columns, &block)
761:         end
762:         cur_sel = [WILDCARD]
763:       end
764:       select(*(cur_sel + columns), &block)
765:     end

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(:c___a){f(c2)}
  # SELECT c AS a, f(c2) FROM items GROUP BY c, f(c2)

[Source]

     # File lib/sequel/dataset/query.rb, line 776
776:     def select_group(*columns, &block)
777:       virtual_row_columns(columns, block)
778:       select(*columns).group(*columns.map{|c| unaliased_identifier(c)})
779:     end

Alias for select_append.

[Source]

     # File lib/sequel/dataset/query.rb, line 782
782:     def select_more(*columns, &block)
783:       select_append(*columns, &block)
784:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 795
795:     def server(servr)
796:       clone(:server=>servr)
797:     end

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.

[Source]

     # File lib/sequel/dataset/query.rb, line 802
802:     def server?(server)
803:       if db.sharded? && !opts[:server]
804:         server(server)
805:       else
806:         self
807:       end
808:     end

Unbind bound variables from this dataset‘s filter and return an array of two objects. The first object is a modified dataset where the filter has been replaced with one that uses bound variable placeholders. The second object is the hash of unbound variables. You can then prepare and execute (or just call) the dataset with the bound variables to get results.

  ds, bv = DB[:items].where(:a=>1).unbind
  ds # SELECT * FROM items WHERE (a = $a)
  bv #  {:a => 1}
  ds.call(:select, bv)

[Source]

     # File lib/sequel/dataset/query.rb, line 820
820:     def unbind
821:       u = Unbinder.new
822:       ds = clone(:where=>u.transform(opts[:where]), :join=>u.transform(opts[:join]))
823:       [ds, u.binds]
824:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 830
830:     def unfiltered
831:       clone(:where => nil, :having => nil)
832:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 838
838:     def ungrouped
839:       clone(:group => nil, :having => nil)
840:     end

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

[Source]

     # File lib/sequel/dataset/query.rb, line 858
858:     def union(dataset, opts=OPTS)
859:       compound_clone(:union, dataset, opts)
860:     end

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

  DB[:items].limit(10, 20).unlimited # SELECT * FROM items

[Source]

     # File lib/sequel/dataset/query.rb, line 865
865:     def unlimited
866:       clone(:limit=>nil, :offset=>nil)
867:     end

Returns a copy of the dataset with no order.

  DB[:items].order(:a).unordered # SELECT * FROM items

[Source]

     # File lib/sequel/dataset/query.rb, line 872
872:     def unordered
873:       order(nil)
874:     end

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

Accepts the following argument types:

Hash :list of equality/inclusion expressions
Array :depends:
  • If first member is a string, assumes the rest of the arguments are parameters and interpolates them into the string.
  • If all members are arrays of length two, treats the same way as a hash, except it allows for duplicate keys to be specified.
  • Otherwise, treats each argument as a separate condition.
String :taken literally
Symbol :taken as a boolean column argument (e.g. WHERE active)
Sequel::SQL::BooleanExpression :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('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('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.

[Source]

     # File lib/sequel/dataset/query.rb, line 926
926:     def where(*cond, &block)
927:       _filter(:where, *cond, &block)
928:     end

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
  DB[:items].with(:items, DB[:syx].where(:name.like('A%')))
  # WITH items AS (SELECT * FROM syx WHERE (name LIKE 'A%' ESCAPE '\')) SELECT * FROM items

[Source]

     # File lib/sequel/dataset/query.rb, line 938
938:     def with(name, dataset, opts=OPTS)
939:       raise(Error, 'This dataset does not support common table expressions') unless supports_cte?
940:       if hoist_cte?(dataset)
941:         s, ds = hoist_cte(dataset)
942:         s.with(name, ds, opts)
943:       else
944:         clone(:with=>(@opts[:with]||[]) + [opts.merge(:name=>name, :dataset=>dataset)])
945:       end
946:     end

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.
  DB[:t].with_recursive(:t,
    DB[:i1].select(:id, :parent_id).where(:parent_id=>nil),
    DB[:i1].join(:t, :id=>:parent_id).select(:i1__id, :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"

[Source]

     # File lib/sequel/dataset/query.rb, line 964
964:     def with_recursive(name, nonrecursive, recursive, opts=OPTS)
965:       raise(Error, 'This datatset does not support common table expressions') unless supports_cte?
966:       if hoist_cte?(nonrecursive)
967:         s, ds = hoist_cte(nonrecursive)
968:         s.with_recursive(name, ds, recursive, opts)
969:       elsif hoist_cte?(recursive)
970:         s, ds = hoist_cte(recursive)
971:         s.with_recursive(name, nonrecursive, ds, opts)
972:       else
973:         clone(:with=>(@opts[:with]||[]) + [opts.merge(:recursive=>true, :name=>name, :dataset=>nonrecursive.union(recursive, {:all=>opts[:union_all] != false, :from_self=>false}))])
974:       end
975:     end

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)

[Source]

     # File lib/sequel/dataset/query.rb, line 989
989:     def with_sql(sql, *args)
990:       if sql.is_a?(Symbol)
991:         sql = send(sql, *args)
992:       else
993:         sql = SQL::PlaceholderLiteralString.new(sql, args) unless args.empty?
994:       end
995:       clone(:sql=>sql)
996:     end

Protected Instance methods

Add the dataset to the list of compounds

[Source]

      # File lib/sequel/dataset/query.rb, line 1001
1001:     def compound_clone(type, dataset, opts)
1002:       if hoist_cte?(dataset)
1003:         s, ds = hoist_cte(dataset)
1004:         return s.compound_clone(type, ds, opts)
1005:       end
1006:       ds = compound_from_self.clone(:compounds=>Array(@opts[:compounds]).map{|x| x.dup} + [[type, dataset.compound_from_self, opts[:all]]])
1007:       opts[:from_self] == false ? ds : ds.from_self(opts)
1008:     end

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

[Source]

      # File lib/sequel/dataset/query.rb, line 1011
1011:     def options_overlap(opts)
1012:       !(@opts.collect{|k,v| k unless v.nil?}.compact & opts).empty?
1013:     end

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

  SELECT * FROM table
  SELECT table.* FROM table

[Source]

      # File lib/sequel/dataset/query.rb, line 1019
1019:     def simple_select_all?
1020:       o = @opts.reject{|k,v| v.nil? || NON_SQL_OPTIONS.include?(k)}
1021:       if (f = o[:from]) && f.length == 1 && (f.first.is_a?(Symbol) || f.first.is_a?(SQL::AliasedExpression))
1022:         case o.length
1023:         when 1
1024:           true
1025:         when 2
1026:           (s = o[:select]) && s.length == 1 && s.first.is_a?(SQL::ColumnAll)
1027:         else
1028:           false
1029:         end
1030:       else
1031:         false
1032:       end
1033:     end

8 - Methods related to prepared statements or bound variables

On some adapters, these use native prepared statements and bound variables, on others support is emulated. For details, see the "Prepared Statements/Bound Variables" guide.

Constants

PREPARED_ARG_PLACEHOLDER = LiteralString.new('?').freeze

Public Instance methods

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].filter(:id=>:$id).bind(:id=>1).call(:first)
  # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
  # => {:id=>1}

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 223
223:     def bind(bind_vars={})
224:       clone(:bind_vars=>@opts[:bind_vars] ? @opts[:bind_vars].merge(bind_vars) : bind_vars)
225:     end

For the given type (:select, :first, :insert, :insert_select, :update, or :delete), 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].filter(:id=>:$id).call(:first, :id=>1)
  # SELECT * FROM table WHERE id = ? LIMIT 1 -- (1)
  # => {:id=>1}

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 234
234:     def call(type, bind_variables={}, *values, &block)
235:       prepare(type, nil, *values).call(bind_variables, &block)
236:     end

Prepare an SQL statement for later execution. Takes a type similar to call, and the name symbol of the prepared statement. While name defaults to nil, it should always be provided as a symbol for the name of the prepared statement, as some databases require that prepared statements have names.

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].filter(: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

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 256
256:     def prepare(type, name=nil, *values)
257:       ps = to_prepared_statement(type, values)
258:       db.set_prepared_statement(name, ps) if name
259:       ps
260:     end

Protected Instance methods

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

[Source]

     # File lib/sequel/dataset/prepared_statements.rb, line 266
266:     def to_prepared_statement(type, values=nil)
267:       ps = bind
268:       ps.extend(PreparedStatementMethods)
269:       ps.orig_dataset = self
270:       ps.prepared_type = type
271:       ps.prepared_modify_values = values
272:       ps
273:     end

7 - Mutation methods

These methods modify the receiving dataset and should be used with care.

Constants

MUTATION_METHODS = QUERY_METHODS - [:naked, :from_self]   All methods that should have a ! method added that modifies the receiver.

Attributes

row_proc  [R]  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.

Public Class methods

Setup mutation (e.g. filter!) methods. These operate the same as the non-! methods, but replace the options of the current dataset with the options of the resulting dataset.

Do not call this method with untrusted input, as that can result in arbitrary code execution.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 17
17:     def self.def_mutation_method(*meths)
18:       options = meths.pop if meths.last.is_a?(Hash)
19:       mod = options[:module] if options
20:       mod ||= self
21:       meths.each do |meth|
22:         mod.class_eval("def #{meth}!(*args, &block); mutation_method(:#{meth}, *args, &block) end", __FILE__, __LINE__)
23:       end
24:     end

Public Instance methods

Load an extension into the receiver. In addition to requiring the extension file, this also modifies the dataset to work with the extension (usually extending it with a module defined in the extension file). If no related extension file exists or the extension does not have specific support for Database objects, an Error will be raised. Returns self.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 38
38:     def extension!(*exts)
39:       raise_if_frozen!
40:       Sequel.extension(*exts)
41:       exts.each do |ext|
42:         if pr = Sequel.synchronize{EXTENSIONS[ext]}
43:           pr.call(self)
44:         else
45:           raise(Error, "Extension #{ext} does not have specific support handling individual datasets")
46:         end
47:       end
48:       self
49:     end

Avoid self-referential dataset by cloning.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 52
52:     def from_self!(*args, &block)
53:       raise_if_frozen!
54:       @opts = clone.from_self(*args, &block).opts
55:       self
56:     end

Set the method to call on identifiers going into the database for this dataset

[Source]

    # File lib/sequel/dataset/mutation.rb, line 59
59:     def identifier_input_method=(v)
60:       raise_if_frozen!
61:       skip_symbol_cache!
62:       @identifier_input_method = v
63:     end

Set the method to call on identifiers coming the database for this dataset

[Source]

    # File lib/sequel/dataset/mutation.rb, line 66
66:     def identifier_output_method=(v)
67:       raise_if_frozen!
68:       @identifier_output_method = v
69:     end

Remove the row_proc from the current dataset.

[Source]

    # File lib/sequel/dataset/mutation.rb, line 72
72:     def naked!
73:       raise_if_frozen!
74:       self.row_proc = nil
75:       self
76:     end

Set whether to quote identifiers for this dataset

[Source]

    # File lib/sequel/dataset/mutation.rb, line 79
79:     def quote_identifiers=(v)
80:       raise_if_frozen!
81:       skip_symbol_cache!
82:       @quote_identifiers = v
83:     end

Override the row_proc for this dataset

[Source]

    # File lib/sequel/dataset/mutation.rb, line 86
86:     def row_proc=(v)
87:       raise_if_frozen!
88:       @row_proc = v
89:     end

6 - Miscellaneous methods

These methods don‘t fit cleanly into another section.

Constants

NOTIMPL_MSG = "This method must be overridden in Sequel adapters".freeze
ARRAY_ACCESS_ERROR_MSG = 'You cannot call Dataset#[] with an integer or with no arguments.'.freeze
ARG_BLOCK_ERROR_MSG = 'Must use either an argument or a block, not both'.freeze
IMPORT_ERROR_MSG = 'Using Sequel::Dataset#import an empty column array is not allowed'.freeze

Attributes

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

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.

[Source]

    # File lib/sequel/dataset/misc.rb, line 28
28:     def initialize(db)
29:       @db = db
30:       @opts = OPTS
31:     end

Public Instance methods

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

[Source]

    # File lib/sequel/dataset/misc.rb, line 35
35:     def ==(o)
36:       o.is_a?(self.class) && db == o.db && opts == o.opts && sql == o.sql
37:     end

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

[Source]

    # File lib/sequel/dataset/misc.rb, line 41
41:     def current_datetime
42:       Sequel.datetime_class.now
43:     end

Similar to clone, but returns an unfrozen clone if the receiver is frozen.

[Source]

    # File lib/sequel/dataset/misc.rb, line 51
51:     def dup
52:       o = clone
53:       o.opts.delete(:frozen)
54:       o
55:     end

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')}

[Source]

    # File lib/sequel/dataset/misc.rb, line 62
62:     def each_server
63:       db.servers.each{|s| yield server(s)}
64:     end

Alias for ==

[Source]

    # File lib/sequel/dataset/misc.rb, line 46
46:     def eql?(o)
47:       self == o
48:     end

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\\\%\_'

[Source]

    # File lib/sequel/dataset/misc.rb, line 71
71:     def escape_like(string)
72:       string.gsub(/[\\%_]/){|m| "\\#{m}"}
73:     end

Alias of first_source_alias

[Source]

    # File lib/sequel/dataset/misc.rb, line 87
87:     def first_source
88:       first_source_alias
89:     end

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[:table___t].first_source_alias
  # => :t

[Source]

     # File lib/sequel/dataset/misc.rb, line 99
 99:     def first_source_alias
100:       source = @opts[:from]
101:       if source.nil? || source.empty?
102:         raise Error, 'No source specified for query'
103:       end
104:       case s = source.first
105:       when SQL::AliasedExpression
106:         s.alias
107:       when Symbol
108:         _, _, aliaz = split_symbol(s)
109:         aliaz ? aliaz.to_sym : s
110:       else
111:         s
112:       end
113:     end

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[:table___t].first_source_table
  # => :table

[Source]

     # File lib/sequel/dataset/misc.rb, line 124
124:     def first_source_table
125:       source = @opts[:from]
126:       if source.nil? || source.empty?
127:         raise Error, 'No source specified for query'
128:       end
129:       case s = source.first
130:       when SQL::AliasedExpression
131:         s.expression
132:       when Symbol
133:         sch, table, aliaz = split_symbol(s)
134:         aliaz ? (sch ? SQL::QualifiedIdentifier.new(sch, table) : table.to_sym) : s
135:       else
136:         s
137:       end
138:     end

Sets the frozen flag on the dataset, so you can‘t modify it. Returns the receiver.

[Source]

    # File lib/sequel/dataset/misc.rb, line 76
76:     def freeze
77:       @opts[:frozen] = true
78:       self
79:     end

Whether the object is frozen.

[Source]

    # File lib/sequel/dataset/misc.rb, line 82
82:     def frozen?
83:       @opts[:frozen]
84:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 142
142:     def hash
143:       [db, opts, sql].hash
144:     end

The String instance method to call on identifiers before sending them to the database.

[Source]

     # File lib/sequel/dataset/misc.rb, line 148
148:     def identifier_input_method
149:       if defined?(@identifier_input_method)
150:         @identifier_input_method
151:       else
152:         @identifier_input_method = db.identifier_input_method
153:       end
154:     end

The String instance method to call on identifiers before sending them to the database.

[Source]

     # File lib/sequel/dataset/misc.rb, line 158
158:     def identifier_output_method
159:       if defined?(@identifier_output_method)
160:         @identifier_output_method
161:       else
162:         @identifier_output_method = db.identifier_output_method
163:       end
164:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 168
168:     def inspect
169:       "#<#{visible_class_name}: #{sql.inspect}>"
170:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 173
173:     def joined_dataset?
174:      !!((opts[:from].is_a?(Array) && opts[:from].size > 1) || opts[:join])
175:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 179
179:     def row_number_column
180:       :x_sequel_row_number_x
181:     end

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.

[Source]

     # File lib/sequel/dataset/misc.rb, line 186
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

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 205
205:     def unqualified_column_for(v)
206:       unless v.is_a?(String)
207:         _unqualified_column_for(v)
208:       end
209:     end

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

[Source]

     # File lib/sequel/dataset/misc.rb, line 233
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:         loop do
240:           ta = "#{table_alias}_#{i}""#{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

5 - Methods related to dataset graphing

Dataset graphing changes the dataset to yield hashes where keys are table name symbols and values are hashes representing the columns related to that table. All of these methods return modified copies of the receiver.

Public Instance methods

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_more when graphing). See set_graph_aliases.

  DB[:table].add_graph_aliases(:some_alias=>[:table, :column])
  # SELECT ..., table.column AS some_alias

[Source]

    # File lib/sequel/dataset/graph.rb, line 16
16:     def add_graph_aliases(graph_aliases)
17:       unless (ga = opts[:graph_aliases]) || (opts[:graph] && (ga = opts[:graph][:column_aliases]))
18:         raise Error, "cannot call add_graph_aliases on a dataset that has not been called with graph or set_graph_aliases"
19:       end
20:       columns, graph_aliases = graph_alias_columns(graph_aliases)
21:       select_more(*columns).clone(:graph_aliases => ga.merge(graph_aliases))
22:     end

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.

[Source]

     # File lib/sequel/dataset/graph.rb, line 50
 50:     def graph(dataset, join_conditions = nil, options = OPTS, &block)
 51:       # Allow the use of a dataset or symbol as the first argument
 52:       # Find the table name/dataset based on the argument
 53:       table_alias = options[:table_alias]
 54:       table = dataset
 55:       create_dataset = true
 56: 
 57:       case dataset
 58:       when Symbol
 59:         # let alias be the same as the table name (sans any optional schema)
 60:         # unless alias explicitly given in the symbol using ___ notation
 61:         table_alias ||= split_symbol(table).compact.last
 62:       when Dataset
 63:         if dataset.simple_select_all?
 64:           table = dataset.opts[:from].first
 65:           table_alias ||= table
 66:         else
 67:           table_alias ||= dataset_alias((@opts[:num_dataset_sources] || 0)+1)
 68:         end
 69:         create_dataset = false
 70:       when SQL::Identifier
 71:         table_alias ||= table.value
 72:       when SQL::QualifiedIdentifier
 73:         table_alias ||= split_qualifiers(table).last
 74:       when SQL::AliasedExpression
 75:         return graph(table.expression, join_conditions, {:table_alias=>table.alias}.merge(options), &block)
 76:       else
 77:         raise Error, "The dataset argument should be a symbol or dataset"
 78:       end
 79:       table_alias = table_alias.to_sym
 80: 
 81:       if create_dataset
 82:         dataset = db.from(table)
 83:       end
 84: 
 85:       # Raise Sequel::Error with explanation that the table alias has been used
 86:       raise_alias_error = lambda do
 87:         raise(Error, "this #{options[:table_alias] ? 'alias' : 'table'} has already been been used, please specify " \
 88:           "#{options[:table_alias] ? 'a different alias' : 'an alias via the :table_alias option'}") 
 89:       end
 90: 
 91:       # Only allow table aliases that haven't been used
 92:       raise_alias_error.call if @opts[:graph] && @opts[:graph][:table_aliases] && @opts[:graph][:table_aliases].include?(table_alias)
 93:       
 94:       table_alias_qualifier = qualifier_from_alias_symbol(table_alias, table)
 95:       implicit_qualifier = options[:implicit_qualifier]
 96:       ds = self
 97: 
 98:       # Use a from_self if this is already a joined table (or from_self specifically disabled for graphs)
 99:       if (@opts[:graph_from_self] != false && !@opts[:graph] && joined_dataset?)
100:         from_selfed = true
101:         implicit_qualifier = options[:from_self_alias] || first_source
102:         ds = ds.from_self(:alias=>implicit_qualifier)
103:       end
104:       
105:       # Join the table early in order to avoid cloning the dataset twice
106:       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)
107: 
108:       return ds if options[:join_only]
109: 
110:       opts = ds.opts
111: 
112:       # Whether to include the table in the result set
113:       add_table = options[:select] == false ? false : true
114:       # Whether to add the columns to the list of column aliases
115:       add_columns = !ds.opts.include?(:graph_aliases)
116: 
117:       if graph = opts[:graph]
118:         opts[:graph] = graph = graph.dup
119:         select = opts[:select].dup
120:         [:column_aliases, :table_aliases, :column_alias_num].each{|k| graph[k] = graph[k].dup}
121:       else
122:         # Setup the initial graph data structure if it doesn't exist
123:         qualifier = ds.first_source_alias
124:         master = alias_symbol(qualifier)
125:         raise_alias_error.call if master == table_alias
126: 
127:         # Master hash storing all .graph related information
128:         graph = opts[:graph] = {}
129: 
130:         # Associates column aliases back to tables and columns
131:         column_aliases = graph[:column_aliases] = {}
132: 
133:         # Associates table alias (the master is never aliased)
134:         table_aliases = graph[:table_aliases] = {master=>self}
135: 
136:         # Keep track of the alias numbers used
137:         ca_num = graph[:column_alias_num] = Hash.new(0)
138: 
139:         # All columns in the master table are never
140:         # aliased, but are not included if set_graph_aliases
141:         # has been used.
142:         if add_columns
143:           if (select = @opts[:select]) && !select.empty? && !(select.length == 1 && (select.first.is_a?(SQL::ColumnAll)))
144:             select = select.map do |sel|
145:               raise Error, "can't figure out alias to use for graphing for #{sel.inspect}" unless column = _hash_key_symbol(sel)
146:               column_aliases[column] = [master, column]
147:               if from_selfed
148:                 # Initial dataset was wrapped in subselect, selected all
149:                 # columns in the subselect, qualified by the subselect alias.
150:                 Sequel.qualify(qualifier, Sequel.identifier(column))
151:               else
152:                 # Initial dataset not wrapped in subslect, just make
153:                 # sure columns are qualified in some way.
154:                 qualified_expression(sel, qualifier)
155:               end
156:             end
157:           else
158:             select = columns.map do |column|
159:               column_aliases[column] = [master, column]
160:               SQL::QualifiedIdentifier.new(qualifier, column)
161:             end
162:           end
163:         end
164:       end
165: 
166:       # Add the table alias to the list of aliases
167:       # Even if it isn't been used in the result set,
168:       # we add a key for it with a nil value so we can check if it
169:       # is used more than once
170:       table_aliases = graph[:table_aliases]
171:       table_aliases[table_alias] = add_table ? dataset : nil
172: 
173:       # Add the columns to the selection unless we are ignoring them
174:       if add_table && add_columns
175:         column_aliases = graph[:column_aliases]
176:         ca_num = graph[:column_alias_num]
177:         # Which columns to add to the result set
178:         cols = options[:select] || dataset.columns
179:         # If the column hasn't been used yet, don't alias it.
180:         # If it has been used, try table_column.
181:         # If that has been used, try table_column_N 
182:         # using the next value of N that we know hasn't been
183:         # used
184:         cols.each do |column|
185:           col_alias, identifier = if column_aliases[column]
186:             column_alias = "#{table_alias}_#{column}""#{table_alias}_#{column}"
187:             if column_aliases[column_alias]
188:               column_alias_num = ca_num[column_alias]
189:               column_alias = "#{column_alias}_#{column_alias_num}""#{column_alias}_#{column_alias_num}" 
190:               ca_num[column_alias] += 1
191:             end
192:             [column_alias, SQL::AliasedExpression.new(SQL::QualifiedIdentifier.new(table_alias_qualifier, column), column_alias)]
193:           else
194:             ident = SQL::QualifiedIdentifier.new(table_alias_qualifier, column)
195:             [column, ident]
196:           end
197:           column_aliases[col_alias] = [table_alias, column]
198:           select.push(identifier)
199:         end
200:       end
201:       add_columns ? ds.select(*select) : ds
202:     end

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 ...

[Source]

     # File lib/sequel/dataset/graph.rb, line 227
227:     def set_graph_aliases(graph_aliases)
228:       columns, graph_aliases = graph_alias_columns(graph_aliases)
229:       ds = select(*columns)
230:       ds.opts[:graph_aliases] = graph_aliases
231:       ds
232:     end

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

[Source]

     # File lib/sequel/dataset/graph.rb, line 236
236:     def ungraphed
237:       clone(:graph=>nil, :graph_aliases=>nil)
238:     end

4 - Methods that describe what the dataset supports

These methods all return booleans, with most describing whether or not the dataset supports a feature.

Public Instance methods

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

[Source]

    # File lib/sequel/dataset/features.rb, line 21
21:     def provides_accurate_rows_matched?
22:       true
23:     end

Whether this dataset quotes identifiers.

[Source]

    # File lib/sequel/dataset/features.rb, line 10
10:     def quote_identifiers?
11:       if defined?(@quote_identifiers)
12:         @quote_identifiers
13:       else
14:         @quote_identifiers = db.quote_identifiers?
15:       end
16:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 27
27:     def recursive_cte_requires_column_aliases?
28:       false
29:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 39
39:     def requires_placeholder_type_specifiers?
40:       false
41:     end

Whether the dataset requires SQL standard datetimes (false by default, as most allow strings with ISO 8601 format).

[Source]

    # File lib/sequel/dataset/features.rb, line 33
33:     def requires_sql_standard_datetimes?
34:       false
35:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 46
46:     def supports_cte?(type=:select)
47:       false
48:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 53
53:     def supports_cte_in_subqueries?
54:       false
55:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 60
60:     def supports_derived_column_lists?
61:       true
62:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 65
65:     def supports_distinct_on?
66:       false
67:     end

Whether the dataset supports CUBE with GROUP BY.

[Source]

    # File lib/sequel/dataset/features.rb, line 70
70:     def supports_group_cube?
71:       false
72:     end

Whether the dataset supports ROLLUP with GROUP BY.

[Source]

    # File lib/sequel/dataset/features.rb, line 75
75:     def supports_group_rollup?
76:       false
77:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 81
81:     def supports_insert_select?
82:       supports_returning?(:insert)
83:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 86
86:     def supports_intersect_except?
87:       true
88:     end

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

[Source]

    # File lib/sequel/dataset/features.rb, line 91
91:     def supports_intersect_except_all?
92:       true
93:     end

Whether the dataset supports the IS TRUE syntax.

[Source]

    # File lib/sequel/dataset/features.rb, line 96
96:     def supports_is_true?
97:       true
98:     end

Whether the dataset supports the JOIN table USING (column1, …) syntax.

[Source]

     # File lib/sequel/dataset/features.rb, line 101
101:     def supports_join_using?
102:       true
103:     end

Whether the dataset supports LATERAL for subqueries in the FROM or JOIN clauses.

[Source]

     # File lib/sequel/dataset/features.rb, line 106
106:     def supports_lateral_subqueries?
107:       false
108:     end

Whether limits are supported in correlated subqueries. True by default.

[Source]

     # File lib/sequel/dataset/features.rb, line 111
111:     def supports_limits_in_correlated_subqueries?
112:       true
113:     end

Whether modifying joined datasets is supported.

[Source]

     # File lib/sequel/dataset/features.rb, line 116
116:     def supports_modifying_joins?
117:       false
118:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 122
122:     def supports_multiple_column_in?
123:       true
124:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 127
127:     def supports_offsets_in_correlated_subqueries?
128:       true
129:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 133
133:     def supports_ordered_distinct_on?
134:       supports_distinct_on?
135:     end

Whether the dataset supports pattern matching by regular expressions.

[Source]

     # File lib/sequel/dataset/features.rb, line 138
138:     def supports_regexp?
139:       false
140:     end

Whether the dataset supports REPLACE syntax, false by default.

[Source]

     # File lib/sequel/dataset/features.rb, line 143
143:     def supports_replace?
144:       false
145:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 149
149:     def supports_returning?(type)
150:       false
151:     end

Whether the database supports SELECT *, column FROM table

[Source]

     # File lib/sequel/dataset/features.rb, line 154
154:     def supports_select_all_and_column?
155:       true
156:     end

Whether the dataset supports timezones in literal timestamps

[Source]

     # File lib/sequel/dataset/features.rb, line 159
159:     def supports_timestamp_timezones?
160:       false
161:     end

Whether the dataset supports fractional seconds in literal timestamps

[Source]

     # File lib/sequel/dataset/features.rb, line 164
164:     def supports_timestamp_usecs?
165:       true
166:     end

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

[Source]

     # File lib/sequel/dataset/features.rb, line 175
175:     def supports_where_true?
176:       true
177:     end

Whether the dataset supports window functions.

[Source]

     # File lib/sequel/dataset/features.rb, line 169
169:     def supports_window_functions?
170:       false
171:     end

2 - Methods that execute code on the database

These methods all execute the dataset‘s SQL on the database. They don‘t return modified datasets, so if used in a method chain they should be the last method called.

Constants

ACTION_METHODS = (<<-METHS).split.map{|x| x.to_sym} << [] all avg count columns columns! delete each empty? fetch_rows first first! get import insert interval last map max min multi_insert paged_each range select_hash select_hash_groups select_map select_order_map single_record single_value sum to_hash to_hash_groups truncate update METHS ).split.map{|x| x.to_sym}   Action methods defined by Sequel that execute code on the database.
OPTS = Sequel::OPTS
DatasetClass = self
DatasetClass = self
PREPARED_ARG_PLACEHOLDER = ':'.freeze
DatasetClass = self
DatasetClass = self

Public Instance methods

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)

[Source]

    # File lib/sequel/dataset/actions.rb, line 23
23:     def <<(arg)
24:       insert(arg)
25:       self
26:     end

Returns the first record matching the conditions. Examples:

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

[Source]

    # File lib/sequel/dataset/actions.rb, line 32
32:     def [](*conditions)
33:       raise(Error, ARRAY_ACCESS_ERROR_MSG) if (conditions.length == 1 and conditions.first.is_a?(Integer)) or conditions.length == 0
34:       first(*conditions)
35:     end

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}

[Source]

    # File lib/sequel/dataset/actions.rb, line 45
45:     def all(&block)
46:       _all(block){|a| each{|r| a << r}}
47:     end

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

[Source]

    # File lib/sequel/dataset/actions.rb, line 56
56:     def avg(column=Sequel.virtual_row(&Proc.new))
57:       aggregate_dataset.get{avg(column).as(:avg)}
58:     end

Execute the given type of statement with the hash of values.

[Source]

     # File lib/sequel/adapters/sqlite.rb, line 354
354:       def call(type, bind_vars={}, *values, &block)
355:         ps = to_prepared_statement(type, values)
356:         ps.extend(BindArgumentMethods)
357:         ps.call(bind_vars, &block)
358:       end

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]

[Source]

    # File lib/sequel/dataset/actions.rb, line 69
69:     def columns
70:       return @columns if @columns
71:       ds = unfiltered.unordered.naked.clone(:distinct => nil, :limit => 1, :offset=>nil)
72:       ds.each{break}
73:       @columns = ds.instance_variable_get(:@columns)
74:       @columns || []
75:     end

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

  DB[:table].columns!
  # => [:id, :name]

[Source]

    # File lib/sequel/dataset/actions.rb, line 82
82:     def columns!
83:       @columns = nil
84:       columns
85:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 98
 98:     def count(arg=(no_arg=true), &block)
 99:       if no_arg
100:         if block
101:           arg = Sequel.virtual_row(&block)
102:           aggregate_dataset.get{count(arg).as(:count)}
103:         else
104:           aggregate_dataset.get{count{}.*.as(:count)}.to_i
105:         end
106:       elsif block
107:         raise Error, 'cannot provide both argument and block to Dataset#count'
108:       else
109:         aggregate_dataset.get{count(arg).as(:count)}
110:       end
111:     end

Deletes the records in the dataset. The returned value should be number of records deleted, but that is adapter dependent.

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 118
118:     def delete(&block)
119:       sql = delete_sql
120:       if uses_returning?(:delete)
121:         returning_fetch_rows(sql, &block)
122:       else
123:         execute_dui(sql)
124:       end
125:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 136
136:     def each
137:       if row_proc = @row_proc
138:         fetch_rows(select_sql){|r| yield row_proc.call(r)}
139:       else
140:         fetch_rows(select_sql){|r| yield r}
141:       end
142:       self
143:     end

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

  DB[:table].empty? # SELECT 1 AS one FROM table LIMIT 1
  # => false

[Source]

     # File lib/sequel/dataset/actions.rb, line 149
149:     def empty?
150:       ds = @opts[:order] ? unordered : self
151:       ds.get(Sequel::SQL::AliasedExpression.new(1, :one)).nil?
152:     end

Yield all rows matching this dataset. If the dataset is set to split multiple statements, yield arrays of hashes one per statement instead of yielding results for all statements as hashes.

[Source]

     # File lib/sequel/adapters/mysql.rb, line 295
295:       def fetch_rows(sql)
296:         execute(sql) do |r|
297:           i = -1
298:           cps = db.conversion_procs
299:           cols = r.fetch_fields.map do |f| 
300:             # Pretend tinyint is another integer type if its length is not 1, to
301:             # avoid casting to boolean if Sequel::MySQL.convert_tinyint_to_bool
302:             # is set.
303:             type_proc = f.type == 1 && cast_tinyint_integer?(f) ? cps[2] : cps[f.type]
304:             [output_identifier(f.name), type_proc, i+=1]
305:           end
306:           @columns = cols.map{|c| c.first}
307:           if opts[:split_multiple_result_sets]
308:             s = []
309:             yield_rows(r, cols){|h| s << h}
310:             yield s
311:           else
312:             yield_rows(r, cols){|h| yield h}
313:           end
314:         end
315:         self
316:       end

Set the columns and yield the hashes to the block.

[Source]

     # File lib/sequel/adapters/swift.rb, line 132
132:       def fetch_rows(sql)
133:         execute(sql) do |res|
134:           col_map = {}
135:           @columns = res.fields.map do |c|
136:             col_map[c] = output_identifier(c)
137:           end
138:           tz = db.timezone if Sequel.application_timezone
139:           res.each do |r|
140:             h = {}
141:             r.each do |k, v|
142:               h[col_map[k]] = case v
143:               when StringIO
144:                 SQL::Blob.new(v.read)
145:               when DateTime
146:                 tz ? Sequel.database_to_application_timestamp(Sequel.send(:convert_input_datetime_no_offset, v, tz)) : v
147:               else
148:                 v
149:               end
150:             end
151:             yield h
152:           end
153:         end
154:         self
155:       end

Yield a hash for each row in the dataset.

[Source]

     # File lib/sequel/adapters/sqlite.rb, line 361
361:       def fetch_rows(sql)
362:         execute(sql) do |result|
363:           i = -1
364:           cps = db.conversion_procs
365:           type_procs = result.types.map{|t| cps[base_type_name(t)]}
366:           cols = result.columns.map{|c| i+=1; [output_identifier(c), i, type_procs[i]]}
367:           @columns = cols.map{|c| c.first}
368:           result.each do |values|
369:             row = {}
370:             cols.each do |name,id,type_proc|
371:               v = values[id]
372:               if type_proc && v
373:                 v = type_proc.call(v)
374:               end
375:               row[name] = v
376:             end
377:             yield row
378:           end
379:         end
380:       end

Yield all rows matching this dataset. If the dataset is set to split multiple statements, yield arrays of hashes one per statement instead of yielding results for all statements as hashes.

[Source]

     # File lib/sequel/adapters/sqlanywhere.rb, line 143
143:       def fetch_rows(sql)
144:         db = @db
145:         cps = db.conversion_procs
146:         api = db.api
147:         execute(sql) do |rs|
148:           convert = (convert_smallint_to_bool and db.convert_smallint_to_bool)
149:           col_infos = []
150:           api.sqlany_num_cols(rs).times do |i|
151:             _, _, name, _, type = api.sqlany_get_column_info(rs, i)
152:             cp = if type == 500
153:               cps[500] if convert
154:             else
155:               cps[type]
156:             end
157:             col_infos << [i, output_identifier(name), cp]
158:           end
159: 
160:           @columns = col_infos.map{|a| a[1]}
161: 
162:           if rs
163:             while api.sqlany_fetch_next(rs) == 1
164:               h = {}
165:               col_infos.each do |i, name, cp|
166:                 _, v = api.sqlany_get_column(rs, i)
167:                 h[name] = cp && v ? cp[v] : v
168:               end
169:               yield h
170:             end
171:           end
172:         end
173:         self
174:       end

If a integer argument is given, it is interpreted as a limit, and then returns all matching records up to that limit. If no argument is passed, it returns the first matching record. If any other type of argument(s) is passed, it is given to 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("id = 3") # SELECT * FROM table WHERE (id = 3) LIMIT 1
  # => {:id=>3}

  DB[:table].first("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("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}]

[Source]

     # File lib/sequel/dataset/actions.rb, line 189
189:     def first(*args, &block)
190:       ds = block ? filter(&block) : self
191: 
192:       if args.empty?
193:         ds.single_record
194:       else
195:         args = (args.size == 1) ? args.first : args
196:         if args.is_a?(Integer)
197:           ds.limit(args).all
198:         else
199:           ds.filter(args).single_record
200:         end
201:       end
202:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 206
206:     def first!(*args, &block)
207:       first(*args, &block) || raise(Sequel::NoMatchingRow)
208:     end

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']

[Source]

     # File lib/sequel/dataset/actions.rb, line 228
228:     def get(column=(no_arg=true; nil), &block)
229:       ds = naked
230:       if block
231:         raise(Error, ARG_BLOCK_ERROR_MSG) unless no_arg
232:         ds = ds.select(&block)
233:         column = ds.opts[:select]
234:         column = nil if column.is_a?(Array) && column.length < 2
235:       else
236:         ds = if column.is_a?(Array)
237:           ds.select(*column)
238:         else
239:           ds.select(auto_alias_expression(column))
240:         end
241:       end
242: 
243:       if column.is_a?(Array)
244:        if r = ds.single_record
245:          r.values_at(*hash_key_symbols(column))
246:        end
247:       else
248:         ds.single_value
249:       end
250:     end

Don‘t allow graphing a dataset that splits multiple statements

[Source]

     # File lib/sequel/adapters/mysql.rb, line 319
319:       def graph(*)
320:         raise(Error, "Can't graph a dataset that splits multiple result sets") if opts[:split_multiple_result_sets]
321:         super
322:       end

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.

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)

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.
:return :When the :value is :primary_key, returns an array of autoincremented primary key values for the rows inserted.
:server :Set the server/shard to use for the transaction and insert queries.
:slice :Same as :commit_every, :commit_every takes precedence.

[Source]

     # File lib/sequel/dataset/actions.rb, line 277
277:     def import(columns, values, opts=OPTS)
278:       return @db.transaction{insert(columns, values)} if values.is_a?(Dataset)
279: 
280:       return if values.empty?
281:       raise(Error, IMPORT_ERROR_MSG) if columns.empty?
282:       ds = opts[:server] ? server(opts[:server]) : self
283:       
284:       if slice_size = opts.fetch(:commit_every, opts.fetch(:slice, default_import_slice))
285:         offset = 0
286:         rows = []
287:         while offset < values.length
288:           rows << ds._import(columns, values[offset, slice_size], opts)
289:           offset += slice_size
290:         end
291:         rows.flatten
292:       else
293:         ds._import(columns, values, opts)
294:       end
295:     end

Inserts values into the associated table. The returned value is generally the value of the primary key for the inserted row, but that is adapter dependent.

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 an 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

[Source]

     # File lib/sequel/dataset/actions.rb, line 332
332:     def insert(*values, &block)
333:       sql = insert_sql(*values)
334:       if uses_returning?(:insert)
335:         returning_fetch_rows(sql, &block)
336:       else
337:         execute_insert(sql)
338:       end
339:     end

Returns the interval between minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.

  DB[:table].interval(:id) # SELECT (max(id) - min(id)) FROM table LIMIT 1
  # => 6
  DB[:table].interval{function(column)} # SELECT (max(function(column)) - min(function(column))) FROM table LIMIT 1
  # => 7

[Source]

     # File lib/sequel/dataset/actions.rb, line 348
348:     def interval(column=Sequel.virtual_row(&Proc.new))
349:       aggregate_dataset.get{(max(column) - min(column)).as(:interval)}
350:     end

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}]

[Source]

     # File lib/sequel/dataset/actions.rb, line 362
362:     def last(*args, &block)
363:       raise(Error, 'No order specified') unless @opts[:order]
364:       reverse.first(*args, &block)
365:     end

Maps column values for each record in the dataset (if a column name 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'], ...]

[Source]

     # File lib/sequel/dataset/actions.rb, line 381
381:     def map(column=nil, &block)
382:       if column
383:         raise(Error, ARG_BLOCK_ERROR_MSG) if block
384:         return naked.map(column) if row_proc
385:         if column.is_a?(Array)
386:           super(){|r| r.values_at(*column)}
387:         else
388:           super(){|r| r[column]}
389:         end
390:       else
391:         super(&block)
392:       end
393:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 402
402:     def max(column=Sequel.virtual_row(&Proc.new))
403:       aggregate_dataset.get{max(column).as(:max)}
404:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 413
413:     def min(column=Sequel.virtual_row(&Proc.new))
414:       aggregate_dataset.get{min(column).as(:min)}
415:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 429
429:     def multi_insert(hashes, opts=OPTS)
430:       return if hashes.empty?
431:       columns = hashes.first.keys
432:       import(columns, hashes.map{|h| columns.map{|c| h[c]}}, opts)
433:     end

Yields each row in the dataset, but interally 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.

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 retreived 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.

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(:table__id).paged_each(:strategy=>:filter,
    :filter_values=>proc{|row, exprs| [row[:id]]}){|row| }
  # SELECT * FROM table ORDER BY id LIMIT 1000
  # SELECT * FROM table WHERE id > 1001 ORDER BY id LIMIT 1000
  # ...

[Source]

     # File lib/sequel/dataset/actions.rb, line 486
486:     def paged_each(opts=OPTS)
487:       unless @opts[:order]
488:         raise Sequel::Error, "Dataset#paged_each requires the dataset be ordered"
489:       end
490:       unless block_given?
491:         return enum_for(:paged_each, opts)
492:       end
493: 
494:       total_limit = @opts[:limit]
495:       offset = @opts[:offset]
496:       if server = @opts[:server]
497:         opts = opts.merge(:server=>server)
498:       end
499: 
500:       rows_per_fetch = opts[:rows_per_fetch] || 1000
501:       strategy = if offset || total_limit
502:         :offset
503:       else
504:         opts[:strategy] || :offset
505:       end
506: 
507:       db.transaction(opts) do
508:         case strategy
509:         when :filter
510:           filter_values = opts[:filter_values] || proc{|row, exprs| exprs.map{|e| row[hash_key_symbol(e)]}}
511:           base_ds = ds = limit(rows_per_fetch)
512:           while ds
513:             last_row = nil
514:             ds.each do |row|
515:               last_row = row
516:               yield row
517:             end
518:             ds = (base_ds.where(ignore_values_preceding(last_row, &filter_values)) if last_row)
519:           end
520:         else
521:           offset ||= 0
522:           num_rows_yielded = rows_per_fetch
523:           total_rows = 0
524: 
525:           while num_rows_yielded == rows_per_fetch && (total_limit.nil? || total_rows < total_limit)
526:             if total_limit && total_rows + rows_per_fetch > total_limit
527:               rows_per_fetch = total_limit - total_rows
528:             end
529: 
530:             num_rows_yielded = 0
531:             limit(rows_per_fetch, offset).each do |row|
532:               num_rows_yielded += 1
533:               total_rows += 1 if total_limit
534:               yield row
535:             end
536: 
537:             offset += rows_per_fetch
538:           end
539:         end
540:       end
541: 
542:       self
543:     end

Prepare the given type of query with the given name and store it in the database. Note that a new native prepared statement is created on each call to this prepared statement.

[Source]

     # File lib/sequel/adapters/sqlite.rb, line 385
385:       def prepare(type, name=nil, *values)
386:         ps = to_prepared_statement(type, values)
387:         ps.extend(PreparedStatementMethods)
388:         if name
389:           ps.prepared_statement_name = name
390:           db.set_prepared_statement(name, ps)
391:         end
392:         ps
393:       end

Returns a Range instance made from the minimum and maximum values for the given column/expression. Uses a virtual row block if no argument is given.

  DB[:table].range(:id) # SELECT max(id) AS v1, min(id) AS v2 FROM table LIMIT 1
  # => 1..10
  DB[:table].interval{function(column)} # SELECT max(function(column)) AS v1, min(function(column)) AS v2 FROM table LIMIT 1
  # => 0..7

[Source]

     # File lib/sequel/dataset/actions.rb, line 552
552:     def range(column=Sequel.virtual_row(&Proc.new))
553:       if r = aggregate_dataset.select{[min(column).as(v1), max(column).as(v2)]}.first
554:         (r[:v1]..r[:v2])
555:       end
556:     end

Returns a hash with key_column values as keys and value_column values as values. Similar to to_hash, but only selects the columns given.

  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 * 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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 573
573:     def select_hash(key_column, value_column)
574:       _select_hash(:to_hash, key_column, value_column)
575:     end

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.

  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 * 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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 592
592:     def select_hash_groups(key_column, value_column)
593:       _select_hash(:to_hash_groups, key_column, value_column)
594:     end

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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 616
616:     def select_map(column=nil, &block)
617:       _select_map(column, false, &block)
618:     end

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. Usually you can do this by calling the as method on the expression and providing an alias.

[Source]

     # File lib/sequel/dataset/actions.rb, line 636
636:     def select_order_map(column=nil, &block)
637:       _select_map(column, true, &block)
638:     end

Returns the first record in the dataset, or nil if the dataset has no records. Users should probably use first instead of this method.

[Source]

     # File lib/sequel/dataset/actions.rb, line 643
643:     def single_record
644:       clone(:limit=>1).each{|r| return r}
645:       nil
646:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 651
651:     def single_value
652:       if r = ungraphed.naked.single_record
653:         r.values.first
654:       end
655:     end

Makes each yield arrays of rows, with each array containing the rows for a given result set. Does not work with graphing. So you can submit SQL with multiple statements and easily determine which statement returned which results.

Modifies the row_proc of the returned dataset so that it still works as expected (running on the hashes instead of on the arrays of hashes). If you modify the row_proc afterward, note that it will receive an array of hashes instead of a hash.

[Source]

     # File lib/sequel/adapters/mysql.rb, line 333
333:       def split_multiple_result_sets
334:         raise(Error, "Can't split multiple statements on a graphed dataset") if opts[:graph]
335:         ds = clone(:split_multiple_result_sets=>true)
336:         ds.row_proc = proc{|x| x.map{|h| row_proc.call(h)}} if row_proc
337:         ds
338:       end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 664
664:     def sum(column=Sequel.virtual_row(&Proc.new))
665:       aggregate_dataset.get{sum(column).as(:sum)}
666:     end

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

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

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 687
687:     def to_hash(key_column, value_column = nil)
688:       h = {}
689:       if value_column
690:         return naked.to_hash(key_column, value_column) if row_proc
691:         if value_column.is_a?(Array)
692:           if key_column.is_a?(Array)
693:             each{|r| h[r.values_at(*key_column)] = r.values_at(*value_column)}
694:           else
695:             each{|r| h[r[key_column]] = r.values_at(*value_column)}
696:           end
697:         else
698:           if key_column.is_a?(Array)
699:             each{|r| h[r.values_at(*key_column)] = r[value_column]}
700:           else
701:             each{|r| h[r[key_column]] = r[value_column]}
702:           end
703:         end
704:       elsif key_column.is_a?(Array)
705:         each{|r| h[r.values_at(*key_column)] = r}
706:       else
707:         each{|r| h[r[key_column]] = r}
708:       end
709:       h
710:     end

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'}, ...], ...}

[Source]

     # File lib/sequel/dataset/actions.rb, line 730
730:     def to_hash_groups(key_column, value_column = nil)
731:       h = {}
732:       if value_column
733:         return naked.to_hash_groups(key_column, value_column) if row_proc
734:         if value_column.is_a?(Array)
735:           if key_column.is_a?(Array)
736:             each{|r| (h[r.values_at(*key_column)] ||= []) << r.values_at(*value_column)}
737:           else
738:             each{|r| (h[r[key_column]] ||= []) << r.values_at(*value_column)}
739:           end
740:         else
741:           if key_column.is_a?(Array)
742:             each{|r| (h[r.values_at(*key_column)] ||= []) << r[value_column]}
743:           else
744:             each{|r| (h[r[key_column]] ||= []) << r[value_column]}
745:           end
746:         end
747:       elsif key_column.is_a?(Array)
748:         each{|r| (h[r.values_at(*key_column)] ||= []) << r}
749:       else
750:         each{|r| (h[r[key_column]] ||= []) << r}
751:       end
752:       h
753:     end

Truncates the dataset. Returns nil.

  DB[:table].truncate # TRUNCATE table
  # => nil

[Source]

     # File lib/sequel/dataset/actions.rb, line 759
759:     def truncate
760:       execute_ddl(truncate_sql)
761:     end

Updates values for the dataset. The returned value is generally the number of rows updated, but that is adapter dependent. values should 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.expr(:x)+1, :y=>0) # UPDATE table SET x = (x + 1), y = 0
  # => 10

[Source]

     # File lib/sequel/dataset/actions.rb, line 773
773:     def update(values=OPTS, &block)
774:       sql = update_sql(values)
775:       if uses_returning?(:update)
776:         returning_fetch_rows(sql, &block)
777:       else
778:         execute_dui(sql)
779:       end
780:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 784
784:     def with_sql_all(sql, &block)
785:       _all(block){|a| with_sql_each(sql){|r| a << r}}
786:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 791
791:     def with_sql_delete(sql)
792:       execute_dui(sql)
793:     end

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

This method should not be called on a shared dataset if the columns selected in the given SQL do not match the columns in the receiver.

[Source]

     # File lib/sequel/dataset/actions.rb, line 800
800:     def with_sql_each(sql)
801:       if row_proc = @row_proc
802:         fetch_rows(sql){|r| yield row_proc.call(r)}
803:       else
804:         fetch_rows(sql){|r| yield r}
805:       end
806:       self
807:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 811
811:     def with_sql_first(sql)
812:       with_sql_each(sql){|r| return r}
813:       nil
814:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 827
827:     def with_sql_insert(sql)
828:       execute_insert(sql)
829:     end

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 819
819:     def with_sql_single_value(sql)
820:       if r = with_sql_first(sql)
821:         r.values.first
822:       end
823:     end
with_sql_update(sql)

Alias for with_sql_delete

Protected Instance methods

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.

[Source]

     # File lib/sequel/dataset/actions.rb, line 836
836:     def _import(columns, values, opts)
837:       trans_opts = opts.merge(:server=>@opts[:server])
838:       if opts[:return] == :primary_key
839:         @db.transaction(trans_opts){values.map{|v| insert(columns, v)}}
840:       else
841:         stmts = multi_insert_sql(columns, values)
842:         @db.transaction(trans_opts){stmts.each{|st| execute_dui(st)}}
843:       end
844:     end

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

[Source]

     # File lib/sequel/dataset/actions.rb, line 847
847:     def _select_map_multiple(ret_cols)
848:       map{|r| r.values_at(*ret_cols)}
849:     end

Returns an array of the first value in each row.

[Source]

     # File lib/sequel/dataset/actions.rb, line 852
852:     def _select_map_single
853:       map{|r| r.values.first}
854:     end