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<?xml version="1.0" encoding="iso-8859-1"?>
<!-- $Revision: 1.5 $ -->
<!-- Generated by xml_proto.php v2.2. Found in /scripts directory of phpdoc. -->
<refentry id="function.db2-rollback">
<refnamediv>
<refname>db2_rollback</refname>
<refpurpose>
Rolls back a transaction
</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>bool</type><methodname>db2_rollback</methodname>
<methodparam><type>resource</type><parameter>connection</parameter></methodparam>
</methodsynopsis>
<para>
Rolls back an in-progress transaction on the specified connection resource and
begins a new transaction. PHP applications normally default to AUTOCOMMIT
mode, so <function>db2_rollback</function> normally has no effect unless
AUTOCOMMIT has been turned off for the connection resource.
</para>
<note>
<para>
If the specified connection resource is a persistent connection, all
transactions in progress for all applications using that persistent
connection will be rolled back. For this reason, persistent connections
are not recommended for use in applications that require transactions.
</para>
</note>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>connection</parameter></term>
<listitem>
<para>
A valid database connection resource variable as returned from
<function>db2_connect</function> or <function>db2_pconnect</function>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
&return.success;
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title>Rolling back a DELETE statement</title>
<para>
In the following example, we count the number of rows in a table, turn
off AUTOCOMMIT mode on a database connection, delete all of the rows in
the table and return the count of <literal>0</literal> to prove that the
rows have been removed. We then issue <function>db2_rollback</function>
and return the updated count of rows in the table to show that the number
is the same as before we issued the DELETE statement. The return to the
original state of the table demonstrates that the roll back of the
transaction succeeded.
</para>
<programlisting role="php">
<![CDATA[
<?php
$conn = db2_connect($database, $user, $password);
if ($conn) {
$stmt = db2_exec($conn, "SELECT count(*) FROM animals");
$res = db2_fetch_array( $stmt );
echo $res[0] . "\n";
// Turn AUTOCOMMIT off
db2_autocommit($conn, DB2_AUTOCOMMIT_OFF);
// Delete all rows from ANIMALS
db2_exec($conn, "DELETE FROM animals");
$stmt = db2_exec($conn, "SELECT count(*) FROM animals");
$res = db2_fetch_array( $stmt );
echo $res[0] . "\n";
// Roll back the DELETE statement
db2_rollback( $conn );
$stmt = db2_exec( $conn, "SELECT count(*) FROM animals" );
$res = db2_fetch_array( $stmt );
echo $res[0] . "\n";
db2_close($conn);
}
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
7
0
7
]]>
</screen>
</example>
</para>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<para>
<simplelist>
<member><function>db2_autocommit</function></member>
<member><function>db2_commit</function></member>
</simplelist>
</para>
</refsect1>
</refentry>
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