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# db2_rollback

(PECL)

db2_rollback -- Rolls back a transaction

## Beschreibung

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.

> Anmerkung: 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.

## Parameter Liste

connection

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

## Rückgabewerte

Gibt bei Erfolg `TRUE` zurück, im Fehlerfall `FALSE`.

## Beispiele

Beispiel 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);
}
?>`

Das oben gezeigte Beispiel erzeugt folgende Ausgabe:

    7
    0
    7

## Siehe auch

db2_autocommit()
db2_commit()

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