module Sequel::SQLite::DatasetMethods
Constants
- CONSTANT_MAP
- EXTRACT_MAP
- INSERT_CONFLICT_RESOLUTIONS
The allowed values for #insert_conflict
Public Instance Methods
# File lib/sequel/adapters/shared/sqlite.rb, line 519 def cast_sql_append(sql, expr, type) if type == Time or type == DateTime sql << "datetime(" literal_append(sql, expr) sql << ')' elsif type == Date sql << "date(" literal_append(sql, expr) sql << ')' else super end 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 535 def complex_expression_sql_append(sql, op, args) case op when :"NOT LIKE", :"NOT ILIKE" sql << 'NOT ' complex_expression_sql_append(sql, (op == :"NOT ILIKE" ? :ILIKE : :LIKE), args) when :^ complex_expression_arg_pairs_append(sql, args){|a, b| Sequel.lit(["((~(", " & ", ")) & (", " | ", "))"], a, b, a, b)} when :** unless (exp = args[1]).is_a?(Integer) raise(Sequel::Error, "can only emulate exponentiation on SQLite if exponent is an integer, given #{exp.inspect}") end case exp when 0 sql << '1' else sql << '(' arg = args[0] if exp < 0 invert = true exp = exp.abs sql << '(1.0 / (' end (exp - 1).times do literal_append(sql, arg) sql << " * " end literal_append(sql, arg) sql << ')' if invert sql << "))" end end when :extract part = args[0] raise(Sequel::Error, "unsupported extract argument: #{part.inspect}") unless format = EXTRACT_MAP[part] sql << "CAST(strftime(" << format << ', ' literal_append(sql, args[1]) sql << ') AS ' << (part == :second ? 'NUMERIC' : 'INTEGER') << ')' else super end 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 580 def constant_sql_append(sql, constant) if c = CONSTANT_MAP[constant] sql << c else super end 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.
# File lib/sequel/adapters/shared/sqlite.rb, line 591 def delete @opts[:where] ? super : where(1=>1).delete 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 598 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 requires GROUP BY on SQLite
# File lib/sequel/adapters/shared/sqlite.rb, line 608 def having(*cond) raise(InvalidOperation, "Can only specify a HAVING clause on a grouped dataset") unless @opts[:group] super 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.
On SQLite 3.24.0+, you can pass a hash to use an ON CONFLICT clause. With out :update option, uses ON CONFLICT DO NOTHING. Options:
- :conflict_where
-
The index filter, when using a partial index to determine uniqueness.
- :target
-
The column name or expression to handle uniqueness violations on.
- :update
-
A hash of columns and values to set. Uses ON CONFLICT DO UPDATE.
- :update_where
-
A WHERE condition to use for the update.
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) DB[:table].insert_conflict({}).insert(a: 1, b: 2) # INSERT INTO TABLE (a, b) VALUES (1, 2) # ON CONFLICT DO NOTHING DB[:table].insert_conflict(target: :a).insert(a: 1, b: 2) # INSERT INTO TABLE (a, b) VALUES (1, 2) # ON CONFLICT (a) DO NOTHING DB[:table].insert_conflict(target: :a, conflict_where: {c: true}).insert(a: 1, b: 2) # INSERT INTO TABLE (a, b) VALUES (1, 2) # ON CONFLICT (a) WHERE (c IS TRUE) DO NOTHING DB[:table].insert_conflict(target: :a, update: {b: Sequel[:excluded][:b]}).insert(a: 1, b: 2) # INSERT INTO TABLE (a, b) VALUES (1, 2) # ON CONFLICT (a) DO UPDATE SET b = excluded.b DB[:table].insert_conflict(target: :a, update: {b: Sequel[:excluded][:b]}, update_where: {Sequel[:table][:status_id] => 1}).insert(a: 1, b: 2) # INSERT INTO TABLE (a, b) VALUES (1, 2) # ON CONFLICT (a) DO UPDATE SET b = excluded.b WHERE (table.status_id = 1)
# File lib/sequel/adapters/shared/sqlite.rb, line 671 def insert_conflict(opts = :ignore) case opts when Symbol, String unless INSERT_CONFLICT_RESOLUTIONS.include?(opts.to_s.upcase) raise Error, "Invalid symbol or string passed to Dataset#insert_conflict: #{opts.inspect}. The allowed values are: :rollback, :abort, :fail, :ignore, or :replace" end clone(:insert_conflict => opts) when Hash clone(:insert_on_conflict => opts) else raise Error, "Invalid value passed to Dataset#insert_conflict: #{opts.inspect}, should use a symbol or a hash" end 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 690 def insert_ignore insert_conflict(:ignore) end
SQLite uses the nonstandard ` (backtick) for quoting identifiers.
# File lib/sequel/adapters/shared/sqlite.rb, line 614 def quoted_identifier_append(sql, c) sql << '`' << c.to_s.gsub('`', '``') << '`' 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 622 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
SQLite 3.8.3+ supports common table expressions.
# File lib/sequel/adapters/shared/sqlite.rb, line 695 def supports_cte?(type=:select) db.sqlite_version >= 30803 end
SQLite supports CTEs in subqueries if it supports CTEs.
# File lib/sequel/adapters/shared/sqlite.rb, line 700 def supports_cte_in_subqueries? supports_cte? end
SQLite does not support table aliases with column aliases
# File lib/sequel/adapters/shared/sqlite.rb, line 705 def supports_derived_column_lists? false end
SQLite does not support INTERSECT ALL or EXCEPT ALL
# File lib/sequel/adapters/shared/sqlite.rb, line 710 def supports_intersect_except_all? false end
SQLite does not support IS TRUE
# File lib/sequel/adapters/shared/sqlite.rb, line 715 def supports_is_true? false end
SQLite does not support multiple columns for the IN/NOT IN operators
# File lib/sequel/adapters/shared/sqlite.rb, line 720 def supports_multiple_column_in? false 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 727 def supports_timestamp_timezones? db.use_timestamp_timezones? end
SQLite cannot use WHERE 't'.
# File lib/sequel/adapters/shared/sqlite.rb, line 732 def supports_where_true? false end
SQLite 3.25+ supports window functions. However, support is only enabled on SQLite 3.26.0+ because internal Sequel usage of window functions to implement eager loading of limited associations triggers an SQLite crash bug in versions 3.25.0-3.25.3.
# File lib/sequel/adapters/shared/sqlite.rb, line 740 def supports_window_functions? db.sqlite_version >= 32600 end
Private Instance Methods
SQLite treats a DELETE with no WHERE clause as a TRUNCATE
# File lib/sequel/adapters/shared/sqlite.rb, line 882 def _truncate_sql(table) "DELETE FROM #{table}" end
If col is a qualified column, alias it to the same as the column name
# File lib/sequel/adapters/shared/sqlite.rb, line 755 def alias_qualified_column(col) case col when Symbol t, c, a = split_symbol(col) if t && !a alias_qualified_column(SQL::QualifiedIdentifier.new(t, c)) else col end when SQL::QualifiedIdentifier SQL::AliasedExpression.new(col, col.column) else col end end
SQLite uses string literals instead of identifiers in AS clauses.
# File lib/sequel/adapters/shared/sqlite.rb, line 747 def as_sql_append(sql, aliaz, column_aliases=nil) raise Error, "sqlite does not support derived column lists" if column_aliases aliaz = aliaz.value if aliaz.is_a?(SQL::Identifier) sql << ' AS ' literal_append(sql, aliaz.to_s) end
SQLite supports a maximum of 500 rows in a VALUES clause.
# File lib/sequel/adapters/shared/sqlite.rb, line 772 def default_import_slice 500 end
SQL fragment specifying a list of identifiers
# File lib/sequel/adapters/shared/sqlite.rb, line 777 def identifier_list(columns) columns.map{|i| quote_identifier(i)}.join(', ') end
Add OR clauses to SQLite INSERT statements
# File lib/sequel/adapters/shared/sqlite.rb, line 782 def insert_conflict_sql(sql) if resolution = @opts[:insert_conflict] sql << " OR " << resolution.to_s.upcase end end
Add ON CONFLICT clause if it should be used
# File lib/sequel/adapters/shared/sqlite.rb, line 789 def insert_on_conflict_sql(sql) if opts = @opts[:insert_on_conflict] sql << " ON CONFLICT" if target = opts[:constraint] sql << " ON CONSTRAINT " identifier_append(sql, target) elsif target = opts[:target] sql << ' ' identifier_append(sql, Array(target)) if conflict_where = opts[:conflict_where] sql << " WHERE " literal_append(sql, conflict_where) end end if values = opts[:update] sql << " DO UPDATE SET " update_sql_values_hash(sql, values) if update_where = opts[:update_where] sql << " WHERE " literal_append(sql, update_where) end else sql << " DO NOTHING" end end end
SQLite uses a preceding X for hex escaping strings
# File lib/sequel/adapters/shared/sqlite.rb, line 819 def literal_blob_append(sql, v) sql << "X'" << v.unpack("H*").first << "'" end
Respect the database integer_booleans setting, using 0 or 'f'.
# File lib/sequel/adapters/shared/sqlite.rb, line 824 def literal_false @db.integer_booleans ? '0' : "'f'" end
Respect the database integer_booleans setting, using 1 or 't'.
# File lib/sequel/adapters/shared/sqlite.rb, line 829 def literal_true @db.integer_booleans ? '1' : "'t'" end
SQLite only supporting multiple rows in the VALUES clause starting in 3.7.11. On older versions, fallback to using a UNION.
# File lib/sequel/adapters/shared/sqlite.rb, line 835 def multi_insert_sql_strategy db.sqlite_version >= 30711 ? :values : :union end
Emulate the char_length function with length
# File lib/sequel/adapters/shared/sqlite.rb, line 840 def native_function_name(emulated_function) if emulated_function == :char_length 'length' else super end end
SQLite does not natively support NULLS FIRST/LAST.
# File lib/sequel/adapters/shared/sqlite.rb, line 849 def requires_emulating_nulls_first? true end
SQLite does not support FOR UPDATE, but silently ignore it instead of raising an error for compatibility with other databases.
# File lib/sequel/adapters/shared/sqlite.rb, line 856 def select_lock_sql(sql) super unless @opts[:lock] == :update end
# File lib/sequel/adapters/shared/sqlite.rb, line 860 def select_only_offset_sql(sql) sql << " LIMIT -1 OFFSET " literal_append(sql, @opts[:offset]) end
Support VALUES clause instead of the SELECT clause to return rows.
# File lib/sequel/adapters/shared/sqlite.rb, line 866 def select_values_sql(sql) sql << "VALUES " expression_list_append(sql, opts[:values]) end
SQLite does not support CTEs directly inside UNION/INTERSECT/EXCEPT.
# File lib/sequel/adapters/shared/sqlite.rb, line 872 def supports_cte_in_compounds? false end
SQLite supports quoted function names.
# File lib/sequel/adapters/shared/sqlite.rb, line 877 def supports_quoted_function_names? true end