How to close PDO Connection in PHP

As with the old MySQL connection, even if you do not close the connection you opened, PHP automatically disconnects at the end of the process. But if you say I will close it, it is enough to define “null”.

<?php
// we opened the connection
$db = new PDO('mysql:host=localhost;dbname=test', $user, $pass);
 
// we closed the connection
$db = null;
?>