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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/delete.sgml,v 1.16 2002/04/23 02:07:16 tgl Exp $
PostgreSQL documentation
-->
<refentry id="SQL-DELETE">
<refmeta>
<refentrytitle id="SQL-DELETE-TITLE">DELETE</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>
DELETE
</refname>
<refpurpose>
delete rows of a table
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>1999-07-20</date>
</refsynopsisdivinfo>
<synopsis>
DELETE FROM [ ONLY ] <replaceable class="PARAMETER">table</replaceable> [ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
</synopsis>
<refsect2 id="R2-SQL-DELETE-1">
<refsect2info>
<date>1998-04-15</date>
</refsect2info>
<title>
Inputs
</title>
<para>
<variablelist>
<varlistentry>
<term><replaceable class="parameter">table</replaceable></term>
<listitem>
<para>
The name (optionally schema-qualified) of an existing table.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="parameter">condition</replaceable></term>
<listitem>
<para>
This is an SQL selection query which returns the rows which
are to be deleted.
</para>
<para>
Refer to the SELECT statement for further description
of the WHERE clause.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
<refsect2 id="R2-SQL-DELETE-2">
<refsect2info>
<date>1998-04-15</date>
</refsect2info>
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
DELETE <replaceable class="parameter">count</replaceable>
</computeroutput></term>
<listitem>
<para>
Message returned if items are successfully deleted. The
<replaceable class="parameter">count</replaceable> is the number
of rows deleted.
</para>
<para>
If <replaceable class="parameter">count</replaceable> is 0,
no rows were deleted.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
</refsynopsisdiv>
<refsect1 id="R1-SQL-DELETE-1">
<refsect1info>
<date>1998-04-15</date>
</refsect1info>
<title>
Description
</title>
<para>
<command>DELETE</command> removes rows which satisfy the WHERE
clause from the specified table.
</para>
<para>
If the <firstterm>condition</firstterm> (WHERE clause) is absent,
the effect is to delete all rows in the table.
The result is a valid, but empty table.
<tip>
<para>
<xref linkend="sql-truncate" endterm="sql-truncate-title"> is a
<productname>PostgreSQL</productname> extension which provides a
faster mechanism to remove all rows from a table.
</para>
</tip>
</para>
<para>
By default DELETE will delete tuples in the table specified
and all its sub-tables. If you wish to only update the
specific table mentioned, you should use the ONLY clause.
</para>
<para>
You must have write access to the table in order to modify
it, as well as read access to any table whose values are
read in the <replaceable class="parameter">condition</replaceable>.
</para>
</refsect1>
<refsect1 id="R1-SQL-DELETE-2">
<title>
Usage
</title>
<para>
Remove all films but musicals:
<programlisting>
DELETE FROM films WHERE kind <> 'Musical';
SELECT * FROM films;
<computeroutput>
code | title | did | date_prod | kind | len
-------+---------------------------+-----+------------+---------+-------
UA501 | West Side Story | 105 | 1961-01-03 | Musical | 02:32
TC901 | The King and I | 109 | 1956-08-11 | Musical | 02:13
WD101 | Bed Knobs and Broomsticks | 111 | | Musical | 01:57
(3 rows)
</computeroutput>
</programlisting>
</para>
<para>
Clear the table <literal>films</literal>:
<programlisting>
DELETE FROM films;
SELECT * FROM films;
<computeroutput>
code | title | did | date_prod | kind | len
------+-------+-----+-----------+------+-----
(0 rows)
</computeroutput>
</programlisting>
</para>
</refsect1>
<refsect1 id="R1-SQL-DELETE-3">
<title>
Compatibility
</title>
<refsect2 id="R2-SQL-DELETE-4">
<refsect2info>
<date>1998-04-15</date>
</refsect2info>
<title>
SQL92
</title>
<para>
<acronym>SQL92</acronym> allows a positioned DELETE statement:
<synopsis>
DELETE FROM <replaceable class="parameter">table</replaceable> WHERE
CURRENT OF <replaceable class="parameter">cursor</replaceable>
</synopsis>
where <replaceable class="parameter">cursor</replaceable>
identifies an open cursor.
Interactive cursors in <productname>PostgreSQL</productname> are read-only.
</para>
</refsect2>
</refsect1>
</refentry>
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