Module | Sequel::SQLite::DatasetMethods |
In: |
lib/sequel/adapters/shared/sqlite.rb
|
Instance methods for datasets that connect to an SQLite database
CONSTANT_MAP | = | {:CURRENT_DATE=>"date(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIMESTAMP=>"datetime(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIME=>"time(CURRENT_TIMESTAMP, 'localtime')".freeze} |
EMULATED_FUNCTION_MAP | = | {:char_length=>'length'.freeze} |
EXTRACT_MAP | = | {:year=>"'%Y'", :month=>"'%m'", :day=>"'%d'", :hour=>"'%H'", :minute=>"'%M'", :second=>"'%f'"} |
NOT_SPACE | = | Dataset::NOT_SPACE |
COMMA | = | Dataset::COMMA |
PAREN_CLOSE | = | Dataset::PAREN_CLOSE |
AS | = | Dataset::AS |
APOS | = | Dataset::APOS |
EXTRACT_OPEN | = | "CAST(strftime(".freeze |
EXTRACT_CLOSE | = | ') AS '.freeze |
NUMERIC | = | 'NUMERIC'.freeze |
INTEGER | = | 'INTEGER'.freeze |
BACKTICK | = | '`'.freeze |
BACKTICK_RE | = | /`/.freeze |
DOUBLE_BACKTICK | = | '``'.freeze |
BLOB_START | = | "X'".freeze |
HSTAR | = | "H*".freeze |
DATE_OPEN | = | "date(".freeze |
DATETIME_OPEN | = | "datetime(".freeze |
ONLY_OFFSET | = | " LIMIT -1 OFFSET ".freeze |
# File lib/sequel/adapters/shared/sqlite.rb, line 521 521: def cast_sql_append(sql, expr, type) 522: if type == Time or type == DateTime 523: sql << DATETIME_OPEN 524: literal_append(sql, expr) 525: sql << PAREN_CLOSE 526: elsif type == Date 527: sql << DATE_OPEN 528: literal_append(sql, expr) 529: sql << PAREN_CLOSE 530: else 531: super 532: end 533: end
SQLite doesn‘t support a NOT LIKE b, you need to use NOT (a LIKE b). It doesn‘t support xor or the extract function natively, so those have to be emulated.
# File lib/sequel/adapters/shared/sqlite.rb, line 537 537: def complex_expression_sql_append(sql, op, args) 538: case op 539: when "NOT LIKE""NOT LIKE", "NOT ILIKE""NOT ILIKE" 540: sql << NOT_SPACE 541: complex_expression_sql_append(sql, (op == "NOT ILIKE""NOT ILIKE" ? :ILIKE : :LIKE), args) 542: when :^ 543: complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.lit(["((~(", " & ", ")) & (", " | ", "))"], a, b, a, b)} 544: when :extract 545: part = args.at(0) 546: raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part] 547: sql << EXTRACT_OPEN << format << COMMA 548: literal_append(sql, args.at(1)) 549: sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE 550: else 551: super 552: end 553: end
SQLite has CURRENT_TIMESTAMP and related constants in UTC instead of in localtime, so convert those constants to local time.
# File lib/sequel/adapters/shared/sqlite.rb, line 557 557: def constant_sql_append(sql, constant) 558: if c = CONSTANT_MAP[constant] 559: sql << c 560: else 561: super 562: end 563: end
Return an array of strings specifying a query explanation for a SELECT of the current dataset. Currently, the options are ignore, but it accepts options to be compatible with other adapters.
# File lib/sequel/adapters/shared/sqlite.rb, line 575 575: def explain(opts=nil) 576: # Load the PrettyTable class, needed for explain output 577: Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable) 578: 579: ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}") 580: rows = ds.all 581: Sequel::PrettyTable.string(rows, ds.columns) 582: end
When a qualified column is selected on SQLite and the qualifier is a subselect, the column name used is the full qualified name (including the qualifier) instead of just the column name. To get correct column names, you must use an alias.
# File lib/sequel/adapters/shared/sqlite.rb, line 599 599: def select(*cols) 600: if ((f = @opts[:from]) && f.any?{|t| t.is_a?(Dataset) || (t.is_a?(SQL::AliasedExpression) && t.expression.is_a?(Dataset))}) || ((j = @opts[:join]) && j.any?{|t| t.table.is_a?(Dataset)}) 601: super(*cols.map{|c| alias_qualified_column(c)}) 602: else 603: super 604: end 605: end
SQLite supports timezones in literal timestamps, since it stores them as text. But using timezones in timestamps breaks SQLite datetime functions, so we allow the user to override the default per database.
# File lib/sequel/adapters/shared/sqlite.rb, line 635 635: def supports_timestamp_timezones? 636: db.use_timestamp_timezones? 637: end