<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.5 $ -->
<!-- splitted from ./en/functions/mysql.xml, last change in rev 1.2 -->
  <refentry id="function.mysql-affected-rows">
   <refnamediv>
    <refname>mysql_affected_rows</refname>
    <refpurpose>Get number of affected rows in previous MySQL
     operation</refpurpose>
   </refnamediv>
   <refsect1>
    <title>Description</title>
     <methodsynopsis>
      <type>int</type><methodname>mysql_affected_rows</methodname>
      <methodparam choice="opt"><type>resource</type><parameter>
        link_identifier
       </parameter></methodparam>
     </methodsynopsis>
    <para>
     <function>mysql_affected_rows</function> returns the number
     of rows affected by the last INSERT, UPDATE or DELETE query
     associated with <parameter>link_identifier</parameter>.  If the
     link identifier isn't specified, the last link opened by
     <function>mysql_connect</function> is assumed.
    </para>
    <note>
     <para>
      If you are using transactions, you need to call
      <function>mysql_affected_rows</function> after your INSERT,
      UPDATE, or DELETE query, not after the commit.
     </para>
    </note>
    <para>
     If the last query was a DELETE query with no WHERE clause, all
     of the records will have been deleted from the table but this
     function will return zero.
    </para>
    <note>
     <para>
      When using UPDATE, MySQL will not update columns where the new
      value is the same as the old value.  This creates the possiblity
      that <function>mysql_affected_rows</function> may not actually
      equal the number of rows matched, only the number of rows that
      were literally affected by the query.
     </para>
    </note>
    <para>
     <function>mysql_affected_rows</function> does not work with
     SELECT statements; only on statements which modify records. To
     retrieve the number of rows returned by a SELECT, use
     <function>mysql_num_rows</function>.
    </para>
    <para>
     If the last query failed, this function will return -1.
     <example>
      <title>Delete-Query</title>
      <programlisting role="php">
<![CDATA[
<?php
    /* connect to database */
    mysql_pconnect("localhost", "mysql_user", "mysql_password") or
        die ("Could not connect");

    /* this should return the correct numbers of deleted records */
    mysql_query("DELETE FROM mytable WHERE id < 10");
    printf ("Records deleted: %d\n", mysql_affected_rows());

    /* without a where clause in a delete statement, it should return 0 */
    mysql_query("DELETE FROM mytable");
    printf ("Records deleted: %d\n", mysql_affected_rows());
?>
]]>
      </programlisting>
      <para>
      The above example would produce the following output:
       <screen>
<![CDATA[
Records deleted: 10
Records deleted: 0
]]>
       </screen>
      </para>
     </example>
     <example>
      <title>Update-Query</title>
      <programlisting role="php">
<![CDATA[
<?php
    /* connect to database */
    mysql_pconnect("localhost", "mysql_user", "mysql_password") or
        die ("Could not connect");

    /* Update records */
    mysql_query("UPDATE mytable SET used=1 WHERE id < 10");
    printf ("Updated records: %d\n", mysql_affected_rows());
mysql_query("COMMIT");
?>
]]>
      </programlisting>
      <para>
       The above example would produce the following output:
       <screen>
<![CDATA[
Updated Records: 10
]]>
       </screen>
      </para>
     </example> 
    </para>
    <para>
     See also: <function>mysql_num_rows</function>,
               <function>mysql_info</function>.
    </para>
   </refsect1>
  </refentry>

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