All moodle courses, ordered by enrollment size

course-size

SELECT course.fullname AS course, COUNT(course.id) AS students FROM mdl_role_assignments AS asg
JOIN mdl_context AS context ON asg.contextid = context.id AND context.contextlevel = 50 JOIN mdl_user AS u ON u.id = asg.userid JOIN mdl_course AS course ON context.instanceid = course.id WHERE asg.roleid = 5 GROUP BY course.id ORDER BY COUNT(course.id) DESC;