Module Sequel::SQLite::DatasetMethods
In: lib/sequel/adapters/shared/sqlite.rb

Instance methods for datasets that connect to an SQLite database

Methods

Constants

SELECT_CLAUSE_METHODS = Dataset.clause_methods(:select, %w'select distinct columns from join where group having compounds order limit')
CONSTANT_MAP = {:CURRENT_DATE=>"date(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIMESTAMP=>"datetime(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIME=>"time(CURRENT_TIMESTAMP, 'localtime')".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
BLOB_START = "X'".freeze
HSTAR = "H*".freeze

Public Instance methods

SQLite does not support pattern matching via regular expressions. SQLite is case insensitive (depending on pragma), so use LIKE for ILIKE.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 424
424:       def complex_expression_sql_append(sql, op, args)
425:         case op
426:         when :~, '!~''!~', '~*''~*', '!~*''!~*'
427:           raise Error, "SQLite does not support pattern matching via regular expressions"
428:         when :ILIKE
429:           super(sql, :LIKE, args.map{|a| SQL::Function.new(:upper, a)})
430:         when "NOT LIKE""NOT LIKE", "NOT ILIKE""NOT ILIKE"
431:           sql << NOT_SPACE
432:           complex_expression_sql_append(sql, (op == "NOT ILIKE""NOT ILIKE" ? :ILIKE : :LIKE), args)
433:         when :^
434:           sql << complex_expression_arg_pairs(args) do |a, b|
435:             a = literal(a)
436:             b = literal(b)
437:             "((~(#{a} & #{b})) & (#{a} | #{b}))"
438:           end
439:         when :extract
440:           part = args.at(0)
441:           raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part]
442:           sql << EXTRACT_OPEN << format << COMMA
443:           literal_append(sql, args.at(1))
444:           sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE
445:         else
446:           super
447:         end
448:       end

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 452
452:       def constant_sql_append(sql, constant)
453:         if c = CONSTANT_MAP[constant]
454:           sql << c
455:         else
456:           super
457:         end
458:       end

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 463
463:       def delete
464:         @opts[:where] ? super : filter(1=>1).delete
465:       end

Return an array of strings specifying a query explanation for a SELECT of the current dataset.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 469
469:       def explain
470:         db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}").
471:           map{|x| "#{x[:addr]}|#{x[:opcode]}|#{(1..5).map{|i| x[:"p#{i}"]}.join('|')}|#{x[:comment]}"}
472:       end

HAVING requires GROUP BY on SQLite

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 475
475:       def having(*cond)
476:         raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
477:         super
478:       end

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

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 481
481:       def quoted_identifier_append(sql, c)
482:         sql << BACKTICK << c.to_s << BACKTICK
483:       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.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 489
489:       def select(*cols)
490:         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)})
491:           super(*cols.map{|c| alias_qualified_column(c)})
492:         else
493:           super
494:         end
495:       end

SQLite does not support INTERSECT ALL or EXCEPT ALL

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 498
498:       def supports_intersect_except_all?
499:         false
500:       end

SQLite does not support IS TRUE

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 503
503:       def supports_is_true?
504:         false
505:       end

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

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 508
508:       def supports_multiple_column_in?
509:         false
510:       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.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 515
515:       def supports_timestamp_timezones?
516:         db.use_timestamp_timezones?
517:       end

SQLite cannot use WHERE ‘t’.

[Source]

     # File lib/sequel/adapters/shared/sqlite.rb, line 520
520:       def supports_where_true?
521:         false
522:       end

[Validate]