delete(7)

NAME#

DELETE - delete rows of a table

SYNOPSIS#

[ WITH [ RECURSIVE ] \nwith_query\n [, ...] ]
DELETE FROM [ ONLY ] \ntable_name\n [ * ] [ [ AS ] \nalias\n ]
\n
    [ USING \nfrom_item\n [, ...] ]
\n
    [ WHERE \ncondition\n | WHERE CURRENT OF \ncursor_name\n ]
\n
    [ RETURNING { * | \noutput_expression\n [ [ AS ] \noutput_name\n ] } [, ...] ]

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.

TRUNCATE 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

table_name

alias

from_item

condition

cursor_name

output_expression

output_name

OUTPUTS#

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

DELETE \ncount

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
\n
  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
\n
  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;

While there is no LIMIT clause for DELETE, it is possible to get a similar effect using the same method described in the documentation of UPDATE:

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

This use of ctid is only safe because the query is repeatedly run, avoiding the problem of changed ctids.

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.

SEE ALSO#

TRUNCATE(7)