DELETE(7)		PostgreSQL 9.2.24 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 9.2.24		  2017-11-06			     DELETE(7)