Module | Sequel::SQLite::DatasetMethods |
In: |
lib/sequel/adapters/shared/sqlite.rb
|
INSERT_CONFLICT_RESOLUTIONS | = | %w'ROLLBACK ABORT FAIL IGNORE REPLACE'.each(&:freeze).freeze | The allowed values for insert_conflict | |
CONSTANT_MAP | = | {:CURRENT_DATE=>"date(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIMESTAMP=>"datetime(CURRENT_TIMESTAMP, 'localtime')".freeze, :CURRENT_TIME=>"time(CURRENT_TIMESTAMP, 'localtime')".freeze}.freeze | ||
EXTRACT_MAP | = | {:year=>"'%Y'", :month=>"'%m'", :day=>"'%d'", :hour=>"'%H'", :minute=>"'%M'", :second=>"'%f'"}.freeze |
# File lib/sequel/adapters/shared/sqlite.rb, line 507 507: def cast_sql_append(sql, expr, type) 508: if type == Time or type == DateTime 509: sql << "datetime(" 510: literal_append(sql, expr) 511: sql << ')' 512: elsif type == Date 513: sql << "date(" 514: literal_append(sql, expr) 515: sql << ')' 516: else 517: super 518: end 519: end
SQLite doesn‘t support a NOT LIKE b, you need to use NOT (a LIKE b). It doesn‘t support xor, power, or the extract function natively, so those have to be emulated.
# File lib/sequel/adapters/shared/sqlite.rb, line 523 523: def complex_expression_sql_append(sql, op, args) 524: case op 525: when "NOT LIKE""NOT LIKE", "NOT ILIKE""NOT ILIKE" 526: sql << 'NOT ' 527: complex_expression_sql_append(sql, (op == "NOT ILIKE""NOT ILIKE" ? :ILIKE : :LIKE), args) 528: when :^ 529: complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.lit(["((~(", " & ", ")) & (", " | ", "))"], a, b, a, b)} 530: when :** 531: unless (exp = args[1]).is_a?(Integer) 532: raise(Sequel::Error, "can only emulate exponentiation on SQLite if exponent is an integer, given #{exp.inspect}") 533: end 534: case exp 535: when 0 536: sql << '1' 537: else 538: sql << '(' 539: arg = args[0] 540: if exp < 0 541: invert = true 542: exp = exp.abs 543: sql << '(1.0 / (' 544: end 545: (exp - 1).times do 546: literal_append(sql, arg) 547: sql << " * " 548: end 549: literal_append(sql, arg) 550: sql << ')' 551: if invert 552: sql << "))" 553: end 554: end 555: when :extract 556: part = args[0] 557: raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part] 558: sql << "CAST(strftime(" << format << ', ' 559: literal_append(sql, args[1]) 560: sql << ') AS ' << (part == :second ? 'NUMERIC' : 'INTEGER') << ')' 561: else 562: super 563: end 564: 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 568 568: def constant_sql_append(sql, constant) 569: if c = CONSTANT_MAP[constant] 570: sql << c 571: else 572: super 573: end 574: end
Return an array of strings specifying a query explanation for a SELECT of the current dataset. Currently, the options are ignored, but it accepts options to be compatible with other adapters.
# File lib/sequel/adapters/shared/sqlite.rb, line 586 586: def explain(opts=nil) 587: # Load the PrettyTable class, needed for explain output 588: Sequel.extension(:_pretty_table) unless defined?(Sequel::PrettyTable) 589: 590: ds = db.send(:metadata_dataset).clone(:sql=>"EXPLAIN #{select_sql}") 591: rows = ds.all 592: Sequel::PrettyTable.string(rows, ds.columns) 593: end
Handle uniqueness violations when inserting, by using a specified resolution algorithm. With no options, uses INSERT OR REPLACE. SQLite supports the following conflict resolution algoriths: ROLLBACK, ABORT, FAIL, IGNORE and REPLACE.
Examples:
DB[:table].insert_conflict.insert(a: 1, b: 2) # INSERT OR IGNORE INTO TABLE (a, b) VALUES (1, 2) DB[:table].insert_conflict(:replace).insert(a: 1, b: 2) # INSERT OR REPLACE INTO TABLE (a, b) VALUES (1, 2)
# File lib/sequel/adapters/shared/sqlite.rb, line 630 630: def insert_conflict(resolution = :ignore) 631: unless INSERT_CONFLICT_RESOLUTIONS.include?(resolution.to_s.upcase) 632: raise Error, "Invalid value passed to Dataset#insert_conflict: #{resolution.inspect}. The allowed values are: :rollback, :abort, :fail, :ignore, or :replace" 633: end 634: clone(:insert_conflict => resolution) 635: end
Ignore uniqueness/exclusion violations when inserting, using INSERT OR IGNORE. Exists mostly for compatibility to MySQL‘s insert_ignore. Example:
DB[:table].insert_ignore.insert(a: 1, b: 2) # INSERT OR IGNORE INTO TABLE (a, b) VALUES (1, 2)
# File lib/sequel/adapters/shared/sqlite.rb, line 642 642: def insert_ignore 643: insert_conflict(:ignore) 644: 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 610 610: def select(*cols) 611: 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)}) 612: super(*cols.map{|c| alias_qualified_column(c)}) 613: else 614: super 615: end 616: 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 679 679: def supports_timestamp_timezones? 680: db.use_timestamp_timezones? 681: end