DELETE(7)						  PostgreSQL 9.2.7 Documentation						 DELETE(7)

NAME

       DELETE - delete rows of a table

SYNOPSIS

       [ WITH [ RECURSIVE ] with_query [, ...] ]
       DELETE FROM [ ONLY ] table_name [ * ] [ [ AS ] alias ]
	   [ USING using_list ]
	   [ WHERE condition | WHERE CURRENT OF cursor_name ]
	   [ RETURNING * | output_expression [ [ AS ] output_name ] [, ...] ]

DESCRIPTION

       DELETE deletes rows that satisfy the WHERE clause from the specified table. If the WHERE clause is absent, the effect is to delete all rows
       in the table. The result is a valid, but empty table.

	   Tip
	   TRUNCATE(7) is a PostgreSQL extension that provides a faster mechanism to remove all rows from a table.

       There are two ways to delete rows in a table using information contained in other tables in the database: using sub-selects, or specifying
       additional tables in the USING clause. Which technique is more appropriate depends on the specific circumstances.

       The optional RETURNING clause causes DELETE to compute and return value(s) based on each row actually deleted. Any expression using the
       table's columns, and/or columns of other tables mentioned in USING, can be computed. The syntax of the RETURNING list is identical to that
       of the output list of SELECT.

       You must have the DELETE privilege on the table to delete from it, as well as the SELECT privilege for any table in the USING clause or
       whose values are read in the condition.

PARAMETERS

       with_query
	   The WITH clause allows you to specify one or more subqueries that can be referenced by name in the DELETE query. See Section 7.8, "WITH
	   Queries (Common Table Expressions)", in the documentation and SELECT(7) for details.

       table_name
	   The name (optionally schema-qualified) of the table to delete rows from. If ONLY is specified before the table name, matching rows are
	   deleted from the named table only. If ONLY is not specified, matching rows are also deleted from any tables inheriting from the named
	   table. Optionally, * can be specified after the table name to explicitly indicate that descendant tables are included.

       alias
	   A substitute name for the target table. When an alias is provided, it completely hides the actual name of the table. For example, given
	   DELETE FROM foo AS f, the remainder of the DELETE statement must refer to this table as f not foo.

       using_list
	   A list of table expressions, allowing columns from other tables to appear in the WHERE condition. This is similar to the list of tables
	   that can be specified in the FROM Clause of a SELECT statement; for example, an alias for the table name can be specified. Do not
	   repeat the target table in the using_list, unless you wish to set up a self-join.

       condition
	   An expression that returns a value of type boolean. Only rows for which this expression returns true will be deleted.

       cursor_name
	   The name of the cursor to use in a WHERE CURRENT OF condition. The row to be deleted is the one most recently fetched from this cursor.
	   The cursor must be a non-grouping query on the DELETE's target table. Note that WHERE CURRENT OF cannot be specified together with a
	   Boolean condition. See DECLARE(7) for more information about using cursors with WHERE CURRENT OF.

       output_expression
	   An expression to be computed and returned by the DELETE command after each row is deleted. The expression can use any column names of
	   the table named by table_name or table(s) listed in USING. Write * to return all columns.

       output_name
	   A name to use for a returned column.

OUTPUTS

       On successful completion, a DELETE command returns a command tag of the form

	   DELETE count

       The count is the number of rows deleted. Note that the number may be less than the number of rows that matched the condition when deletes
       were suppressed by a BEFORE DELETE trigger. If count is 0, no rows were deleted by the query (this is not considered an error).

       If the DELETE command contains a RETURNING clause, the result will be similar to that of a SELECT statement containing the columns and
       values defined in the RETURNING list, computed over the row(s) deleted by the command.

NOTES

       PostgreSQL lets you reference columns of other tables in the WHERE condition by specifying the other tables in the USING clause. For
       example, to delete all films produced by a given producer, one can do:

	   DELETE FROM films USING producers
	     WHERE producer_id = producers.id AND producers.name = 'foo';

       What is essentially happening here is a join between films and producers, with all successfully joined films rows being marked for
       deletion. This syntax is not standard. A more standard way to do it is:

	   DELETE FROM films
	     WHERE producer_id IN (SELECT id FROM producers WHERE name = 'foo');

       In some cases the join style is easier to write or faster to execute than the sub-select style.

EXAMPLES

       Delete all films but musicals:

	   DELETE FROM films WHERE kind <> 'Musical';

       Clear the table films:

	   DELETE FROM films;

       Delete completed tasks, returning full details of the deleted rows:

	   DELETE FROM tasks WHERE status = 'DONE' RETURNING *;

       Delete the row of tasks on which the cursor c_tasks is currently positioned:

	   DELETE FROM tasks WHERE CURRENT OF c_tasks;

COMPATIBILITY

       This command conforms to the SQL standard, except that the USING and RETURNING clauses are PostgreSQL extensions, as is the ability to use
       WITH with DELETE.

PostgreSQL 9.2.7						    2014-02-17								 DELETE(7)