Module: Sequel::SQLite::DatasetMethods

Included in:
Amalgalite::Dataset, Dataset, Sequel::Swift::SQLite::Dataset
Defined in:
lib/sequel/adapters/shared/sqlite.rb

Overview

Instance methods for datasets that connect to an SQLite database

Constant Summary collapse

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
BACKTICK_RE = 
/`/.freeze
DOUBLE_BACKTICK = 
'``'.freeze
BLOB_START = 
"X'".freeze
HSTAR = 
"H*".freeze

Instance Method Summary collapse

Instance Method Details

#complex_expression_sql_append(sql, op, args) ⇒ Object

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



445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 445

def complex_expression_sql_append(sql, op, args)
  case op
  when :~, :'!~', :'~*', :'!~*'
    raise Error, "SQLite does not support pattern matching via regular expressions"
  when :ILIKE
    super(sql, :LIKE, args.map{|a| SQL::Function.new(:upper, a)})
  when :"NOT LIKE", :"NOT ILIKE"
    sql << NOT_SPACE
    complex_expression_sql_append(sql, (op == :"NOT ILIKE" ? :ILIKE : :LIKE), args)
  when :^
    sql << complex_expression_arg_pairs(args) do |a, b|
      a = literal(a)
      b = literal(b)
      "((~(#{a} & #{b})) & (#{a} | #{b}))"
    end
  when :extract
    part = args.at(0)
    raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part]
    sql << EXTRACT_OPEN << format << COMMA
    literal_append(sql, args.at(1))
    sql << EXTRACT_CLOSE << (part == :second ? NUMERIC : INTEGER) << PAREN_CLOSE
  else
    super
  end
end

#constant_sql_append(sql, constant) ⇒ Object

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



473
474
475
476
477
478
479
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 473

def constant_sql_append(sql, constant)
  if c = CONSTANT_MAP[constant]
    sql << c
  else
    super
  end
end

#delete ⇒ Object

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.



484
485
486
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 484

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

#explain(opts = nil) ⇒ Object

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.



491
492
493
494
495
496
497
498
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 491

def explain(opts=nil)
  # Load the PrettyTable class, needed for explain output
  Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable)

  ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}")
  rows = ds.all
  Sequel::PrettyTable.string(rows, ds.columns)
end

#having(*cond) ⇒ Object

HAVING requires GROUP BY on SQLite

Raises:



501
502
503
504
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 501

def having(*cond)
  raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group]
  super
end

#quoted_identifier_append(sql, c) ⇒ Object

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



507
508
509
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 507

def quoted_identifier_append(sql, c)
  sql << BACKTICK << c.to_s.gsub(BACKTICK_RE, DOUBLE_BACKTICK) << BACKTICK
end

#select(*cols) ⇒ Object

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.



515
516
517
518
519
520
521
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 515

def select(*cols)
  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)})
    super(*cols.map{|c| alias_qualified_column(c)})
  else
    super
  end
end

#supports_intersect_except_all? ⇒ Boolean

SQLite does not support INTERSECT ALL or EXCEPT ALL

Returns:

  • (Boolean) 


524
525
526
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 524

def supports_intersect_except_all?
  false
end

#supports_is_true? ⇒ Boolean

SQLite does not support IS TRUE

Returns:

  • (Boolean) 


529
530
531
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 529

def supports_is_true?
  false
end

#supports_multiple_column_in? ⇒ Boolean

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

Returns:

  • (Boolean) 


534
535
536
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 534

def supports_multiple_column_in?
  false
end

#supports_timestamp_timezones? ⇒ Boolean

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.

Returns:

  • (Boolean) 


541
542
543
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 541

def supports_timestamp_timezones?
  db.use_timestamp_timezones?
end

#supports_where_true? ⇒ Boolean

SQLite cannot use WHERE ‘t’.

Returns:

  • (Boolean) 


546
547
548
 
# File 'lib/sequel/adapters/shared/sqlite.rb', line 546

def supports_where_true?
  false
end