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DELETE

DELETE — delete rows of a table

Synopsis

[ WITH [ RECURSIVE ]with_query [, ...] ]DELETE FROM [ ONLY ]table_name [ * ] [ [ AS ]alias ]    [ USINGfrom_item [, ...] ]    [ WHEREcondition | WHERE CURRENT OFcursor_name ]    [ RETURNING [ WITH ( { OLD | NEW } ASoutput_alias [, ...] ) ]                { * |output_expression [ [ AS ]output_name ] } [, ...] ]

Description

DELETE deletes rows that satisfy theWHERE clause from the specified table. If theWHERE clause is absent, the effect is to delete all rows in the table. The result is a valid, but empty 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 theUSING clause. Which technique is more appropriate depends on the specific circumstances.

The optionalRETURNING clause causesDELETE 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 inUSING, can be computed. The syntax of theRETURNING list is identical to that of the output list ofSELECT.

You must have theDELETE privilege on the table to delete from it, as well as theSELECT privilege for any table in theUSING clause or whose values are read in thecondition.

Parameters

Outputs

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

DELETEcount

Thecount is the number of rows deleted. Note that the number may be less than the number of rows that matched thecondition when deletes were suppressed by aBEFORE DELETE trigger. Ifcount is 0, no rows were deleted by the query (this is not considered an error).

If theDELETE command contains aRETURNING clause, the result will be similar to that of aSELECT statement containing the columns and values defined in theRETURNING list, computed over the row(s) deleted by the command.

Notes

PostgreSQL lets you reference columns of other tables in theWHERE condition by specifying the other tables in theUSING 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 betweenfilms andproducers, with all successfully joinedfilms 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 tablefilms:

DELETE FROM films;

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

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

Delete the row oftasks on which the cursorc_tasks is currently positioned:

DELETE FROM tasks WHERE CURRENT OF c_tasks;

While there is noLIMIT clause forDELETE, it is possible to get a similar effect using the same method described inthe documentation ofUPDATE:

WITH delete_batch AS (  SELECT l.ctid FROM user_logs AS l    WHERE l.status = 'archived'    ORDER BY l.creation_date    FOR UPDATE    LIMIT 10000)DELETE FROM user_logs AS dl  USING delete_batch AS del  WHERE dl.ctid = del.ctid;

Compatibility

This command conforms to theSQL standard, except that theUSING andRETURNING clauses arePostgreSQL extensions, as is the ability to useWITH withDELETE.

See Also