Name
DELETE -- delete rows of a tableSynopsis
[ 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 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
WITHclause allows you to specify one or more subqueries that can be referenced by name in theDELETEquery. See Section 7.8 and SELECT for details. table_name-
The name (optionally schema-qualified) of the table to delete rows from. If
ONLYis specified before the table name, matching rows are deleted from the named table only. IfONLYis 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 theDELETEstatement must refer to this table asfnotfoo. using_list-
A list of table expressions, allowing columns from other tables to appear in the
WHEREcondition. This is similar to the list of tables that can be specified in the FROM Clause of aSELECTstatement; for example, an alias for the table name can be specified. Do not repeat the target table in theusing_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 returnstruewill be deleted. cursor_name-
The name of the cursor to use in a
WHERE CURRENT OFcondition. The row to be deleted is the one most recently fetched from this cursor. The cursor must be a non-grouping query on theDELETE's target table. Note thatWHERE CURRENT OFcannot be specified together with a Boolean condition. See DECLARE for more information about using cursors withWHERE CURRENT OF. output_expression-
An expression to be computed and returned by the
DELETEcommand after each row is deleted. The expression can use any column names of the table named bytable_nameor table(s) listed inUSING. 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.
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