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DELETE(7)                        SQL Commands                        DELETE(7)



NAME
       DELETE - delete rows of a table


SYNOPSIS
       DELETE FROM [ ONLY ] table [ * ] [ [ AS ] alias ]
           [ USING usinglist ]
           [ 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 [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 ta-
       ble in the USING clause or whose values are read in the condition.

PARAMETERS
       table  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.

       usinglist
              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 [select(7)] of a SELECT state-
              ment;  for  example, an alias for the table name can be specified. Do not repeat the target table in the
              usinglist, 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
              [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  expres-
              sion  can use any column names of the table 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. If count is 0, no rows matched the condition (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  com-
       mand.

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 exten-
       sions.



SQL - Language Statements         2014-02-17                         DELETE(7)