Database Commit¶
A database commit makes a transaction’s changes permanent. Once committed, the modifications are durable and visible to other connections.
A commit is issued via a call to a commit method, such as PDO::commit() or mysqli_commit() after a sequence of statements executed inside a transaction started with PDO::beginTransaction() or mysqli_query(). If any step fails, PDO::rollBack() or mysqli_rollback() reverts all changes.
Auto-commit mode is enabled by default in PDO: each statement is immediately committed unless an explicit transaction is open.
Each database extension has its own commit method. There are often an auto-commit mode, where the commit is implicit after each query: it must be disabled to allow multiple queries in the same transaction.
<?php
$pdo = new PDO('mysql:host=localhost;dbname=shop', 'user', 'pass');
try {
$pdo->beginTransaction();
$pdo->exec("UPDATE accounts SET balance = balance - 100 WHERE id = 1");
$pdo->exec("UPDATE accounts SET balance = balance + 100 WHERE id = 2");
$pdo->commit();
} catch (Exception $e) {
$pdo->rollBack();
throw $e;
}
?>
Related : Transaction, Rollback, Database, PHP Data Objects (PDO), Atomic Operation, Commit
