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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)
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