Load the correct database class file.
This function is used to load the database class file either at runtime or by wp-admin/setup-config.php We must globalise $wpdb to ensure that it is defined globally by the inline code in wp-db.php.
<?php require_wp_db() ?>
None.
Since: 2.5.0
require_wp_db() is located in /wp-includes/load.php
.