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<!--
$Header: /cvsroot/pgsql/doc/src/sgml/ref/update.sgml,v 1.20 2002/08/15 02:59:18 momjian Exp $
PostgreSQL documentation
-->
<refentry id="SQL-UPDATE">
<refmeta>
<refentrytitle id="SQL-UPDATE-TITLE">UPDATE</refentrytitle>
<refmiscinfo>SQL - Language Statements</refmiscinfo>
</refmeta>
<refnamediv>
<refname>
UPDATE
</refname>
<refpurpose>
update rows of a table
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<refsynopsisdivinfo>
<date>1999-07-20</date>
</refsynopsisdivinfo>
<synopsis>
UPDATE [ ONLY ] <replaceable class="PARAMETER">table</replaceable> SET <replaceable class="PARAMETER">col</replaceable> = <replaceable class="PARAMETER">expression</replaceable> [, ...]
[ FROM <replaceable class="PARAMETER">fromlist</replaceable> ]
[ WHERE <replaceable class="PARAMETER">condition</replaceable> ]
</synopsis>
<refsect2 id="R2-SQL-UPDATE-1">
<refsect2info>
<date>1998-09-24</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. If
<literal>ONLY</> is specified, only that table is updated. If
<literal>ONLY</> is not specified, the table and all its
descendant tables (if any) are updated. <literal>*</> can be
appended to the table name to indicate that descendant tables are
to be scanned, but in the current version, this is the default
behavior. (In releases before 7.1, <literal>ONLY</> was the
default behavior.) The default can be altered by changing the
<option>SQL_INHERITANCE</option> configuration option.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">column</replaceable></term>
<listitem>
<para>
The name of a column in <replaceable class="PARAMETER">table</replaceable>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">expression</replaceable></term>
<listitem>
<para>
A valid expression or value to assign to column.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">fromlist</replaceable></term>
<listitem>
<para>
A <productname>PostgreSQL</productname>
non-standard extension to allow columns
from other tables to appear in the WHERE condition.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><replaceable class="PARAMETER">condition</replaceable></term>
<listitem>
<para>
Refer to the SELECT statement for a further description
of the WHERE clause.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
<refsect2 id="R2-SQL-UPDATE-2">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
Outputs
</title>
<para>
<variablelist>
<varlistentry>
<term><computeroutput>
UPDATE <replaceable class="parameter">#</replaceable>
</computeroutput></term>
<listitem>
<para>
Message returned if successful.
The <replaceable class="parameter">#</replaceable>
means the number of rows updated.
If <replaceable class="parameter">#</replaceable>
is 0 no rows are updated.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect2>
</refsynopsisdiv>
<refsect1 id="R1-SQL-UPDATE-1">
<refsect1info>
<date>1998-09-24</date>
</refsect1info>
<title>
Description
</title>
<para>
<command>UPDATE</command> changes the values of the columns specified for
all rows which satisfy condition. Only the columns
to be modified need appear as columns in the statement.
</para>
<para>
Array references use the same syntax found in
<xref linkend="sql-select" endterm="sql-select-title">.
That is, either single array elements, a range of array
elements or the entire array may be replaced with a single
query.
</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
mentioned in the WHERE condition.
</para>
<para>
By default UPDATE will update 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>
</refsect1>
<refsect1 id="R1-SQL-UPDATE-2">
<title>
Usage
</title>
<para>
Change word <literal>Drama</> with <literal>Dramatic</> on column <structfield>kind</>:
<programlisting>
UPDATE films
SET kind = 'Dramatic'
WHERE kind = 'Drama';
SELECT *
FROM films
WHERE kind = 'Dramatic' OR kind = 'Drama';
code | title | did | date_prod | kind | len
-------+---------------+-----+------------+----------+-------
BL101 | The Third Man | 101 | 1949-12-23 | Dramatic | 01:44
P_302 | Becket | 103 | 1964-02-03 | Dramatic | 02:28
M_401 | War and Peace | 104 | 1967-02-12 | Dramatic | 05:57
T_601 | Yojimbo | 106 | 1961-06-16 | Dramatic | 01:50
DA101 | Das Boot | 110 | 1981-11-11 | Dramatic | 02:29
</programlisting>
</para>
</refsect1>
<refsect1 id="R1-SQL-UPDATE-3">
<title>
Compatibility
</title>
<refsect2 id="R2-SQL-UPDATE-4">
<refsect2info>
<date>1998-09-24</date>
</refsect2info>
<title>
SQL92
</title>
<para>
<acronym>SQL92</acronym> defines a different syntax for
the positioned UPDATE statement:
<synopsis>
UPDATE <replaceable>table</replaceable> SET <replaceable>column</replaceable> = <replaceable>expression</replaceable> [, ...]
WHERE CURRENT OF <replaceable class="parameter">cursor</replaceable>
</synopsis>
where <replaceable class="parameter">cursor</replaceable>
identifies an open cursor.
</para>
</refsect2>
</refsect1>
</refentry>
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