db2_rollback

db2_rollback

(PECL)

db2_rollback --  Rolls back a transaction

Description

bool db2_rollback ( resource connection )

Rolls back an in-progress transaction on the specified connection resource and begins a new transaction. PHP applications normally default to AUTOCOMMIT mode, so db2_rollback() normally has no effect unless AUTOCOMMIT has been turned off for the connection resource.

Note: 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.

Parameters

connection

A valid database connection resource variable as returned from db2_connect() or db2_pconnect().

Return Values

Returns TRUE on success or FALSE on failure.

Examples

Example 1. Rolling back a DELETE statement

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 0 to prove that the rows have been removed. We then issue db2_rollback() 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.

<?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);
}
?>

The above example will output:

7
0
7

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