In what situations should require_once be used over include_once in PHP programming, especially when dealing with essential components like database connection files?

When dealing with essential components like database connection files in PHP programming, it is recommended to use require_once over include_once. This is because require_once will cause a fatal error if the file cannot be included, ensuring that the essential component is loaded successfully. This is crucial for components like database connections that are necessary for the proper functioning of the application.

<?php
require_once 'database_connection.php';

// Your code that relies on the database connection
?>