Module: Sequel::SQLite::DatasetMethods

Constants

 Dataset.clause_methods(:select, %w'select distinct columns from join where group having compounds order limit')
 {:CURRENT_DATE=>"date(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIMESTAMP=>"datetime(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIME=>"time(CURRENT_TIMESTAMP, 'localtime')".freeze}
 {:char_length=>'length'.freeze}
 {:year=>"'%Y'", :month=>"'%m'", :day=>"'%d'", :hour=>"'%H'", :minute=>"'%M'", :second=>"'%f'"}
 Dataset::NOT_SPACE
 Dataset::COMMA
 Dataset::PAREN_CLOSE
 Dataset::AS
 Dataset::APOS
 "CAST(strftime(".freeze
 ') AS '.freeze
 'NUMERIC'.freeze
 'INTEGER'.freeze
 '`'.freeze
 /`/.freeze
 '``'.freeze
 "X'".freeze
 "H*".freeze
 "date(".freeze
 "datetime(".freeze

Public Instance methods

cast_sql_append(sql, expr, type)

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 497
497:       def cast_sql_append(sql, expr, type)
498:         if type == Time or type == DateTime
499:           sql << DATETIME_OPEN
500:           literal_append(sql, expr)
501:           sql << PAREN_CLOSE
502:         elsif type == Date
503:           sql << DATE_OPEN
504:           literal_append(sql, expr)
505:           sql << PAREN_CLOSE
506:         else
507:           super
508:         end
509:       end

complex_expression_sql_append(sql, op, args)

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.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 513
513:       def complex_expression_sql_append(sql, op, args)
514:         case op
515:         when "NOT LIKE""NOT LIKE", "NOT ILIKE""NOT ILIKE"
516:           sql << NOT_SPACE
517:           complex_expression_sql_append(sql, (op == "NOT ILIKE""NOT ILIKE" ? :ILIKE : :LIKE), args)
518:         when :^
519:           sql << complex_expression_arg_pairs(args) do |a, b|
520:             a = literal(a)
521:             b = literal(b)
522:             "((~(#{a} & #{b})) & (#{a} | #{b}))"
523:           end
524:         when :extract
525:           part = args.at(0)
526:           raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part]
527:           sql << EXTRACT_OPEN << format << COMMA
528:           literal_append(sql, args.at(1))
529:           sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE
530:         else
531:           super
532:         end
533:       end

constant_sql_append(sql, constant)

SQLite has CURRENT_TIMESTAMP and related constants in UTC instead of in localtime, so convert those constants to local time.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 537
537:       def constant_sql_append(sql, constant)
538:         if c = CONSTANT_MAP[constant]
539:           sql << c
540:         else
541:           super
542:         end
543:       end

delete()

SQLite performs a TRUNCATE style DELETE if no filter is specified. Since we want to always return the count of records, add a condition that is always true and then delete.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 548
548:       def delete
549:         @opts[:where] ? super : where(1=>1).delete
550:       end

explain(opts=nil)

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.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 555
555:       def explain(opts=nil)
556:         # Load the PrettyTable class, needed for explain output
557:         Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable)
558: 
559:         ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}")
560:         rows = ds.all
561:         Sequel::PrettyTable.string(rows, ds.columns)
562:       end

having(*cond)

HAVING requires GROUP BY on SQLite

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 565
565:       def having(*cond)
566:         raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
567:         super
568:       end

quoted_identifier_append(sql, c)

SQLite uses the nonstandard ` (backtick) for quoting identifiers.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 571
571:       def quoted_identifier_append(sql, c)
572:         sql << BACKTICK << c.to_s.gsub(BACKTICK_RE, DOUBLE_BACKTICK) << BACKTICK
573:       end

select(*cols)

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.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 579
579:       def select(*cols)
580:         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)})
581:           super(*cols.map{|c| alias_qualified_column(c)})
582:         else
583:           super
584:         end
585:       end

supports_intersect_except_all?()

SQLite does not support INTERSECT ALL or EXCEPT ALL

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 588
588:       def supports_intersect_except_all?
589:         false
590:       end

supports_is_true?()

SQLite does not support IS TRUE

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 593
593:       def supports_is_true?
594:         false
595:       end

supports_multiple_column_in?()

SQLite does not support multiple columns for the IN/NOT IN operators

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 598
598:       def supports_multiple_column_in?
599:         false
600:       end

supports_timestamp_timezones?()

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.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 605
605:       def supports_timestamp_timezones?
606:         db.use_timestamp_timezones?
607:       end

supports_where_true?()

SQLite cannot use WHERE ‘t’.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 610
610:       def supports_where_true?
611:         false
612:       end