Instead of editing the basic code of WordPress, as was my plan earlier today, I thought of a solution that involves a subselect in the query of the plugin.
This plugin, WordPress Users (WPU), displays information on the registered users of the website on a given page. As I want to choose the order in which the users are display, I've added a custom profile-field 'level', that is stored into the wp_usermeta table.
Below is the query of WPU that selects the users:
SELECT ID, user_nicename FROM $wpdb->users WHERE ID = ANY (SELECT user_id FROM $wpdb->usermeta WHERE meta_value IN ($roles)) ORDER BY user_nicename LIMIT $offset, $usersPerPage
Although I tried a few things, I can't get it to ORDER BY the 'level'-field in the wb_usermeta table. Maybe one of you can?
Thanks in advance,