Index for Section 5

Alphabetical listing for D

Bottom of page

DELETE()
NAME
  DELETE - delete rows of a table

SYNOPSIS
  DELETE FROM [ ONLY ] table [ WHERE condition ]

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(5)] is a PostgreSQL extension that provides a
       faster mechanism to remove all rows from a table.

  By default, DELETE will delete rows in the specified table and all its
  subtables. If you wish to delete only from the specific table mentioned,
  you must use the ONLY clause.

  You must have the DELETE privilege on the table to delete from it, as well
  as the SELECT privilege for any table whose values are read in the
  condition.

PARAMETERS
  table
       The name (optionally schema-qualified) of an existing table.

  condition
       A value expression that returns a value of type boolean that
       determines the rows which are to be deleted.

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).

NOTES
  PostgreSQL lets you reference columns of other tables in the WHERE
  condition. For example, to delete all films produced by a given producer,
  one might do

  DELETE FROM films
    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. One objection to the join style is that there is no
  explicit list of what tables are being used, which makes the style somewhat
  error-prone; also it cannot handle self-joins.

EXAMPLES
  Delete all films but musicals:

  DELETE FROM films WHERE kind <> 'Musical';

  Clear the table films:

  DELETE FROM films;

COMPATIBILITY
  This command conforms to the SQL standard, except that the ability to
  reference other tables in the WHERE clause is a PostgreSQL extension.

Index for Section 5

Alphabetical listing for D

Top of page