// First, start a transaction $db->beginTransaction(); try { // Execute some SQL queries - insert, update, delete, etc. $db->exec("INSERT INTO employees (name, age) VALUES ('John Doe', 30)"); $db->exec("UPDATE employees SET age = 29 WHERE name = 'Jane Smith'"); // Commit the transaction if everything is successful $db->commit(); } catch(PDOException $e) { // If there's an error, rollBack to undo the changes made so far $db->rollBack(); }In this code example, we start a transaction using the `beginTransaction()` function. We then execute some SQL queries and if all goes well, we commit the transaction using `commit()`. However, if there's an error while executing the queries, we catch the `PDOException` exception and roll back the changes made in the transaction using `rollBack()`. The package library used in this example is probably PDO (PHP Data Objects) as it provides a consistent interface for accessing databases in PHP and includes support for transactions.