group by ·Ö×éºó£¬²éѯµÄ×Ö¶a56爆大奖在线娱乐»°ãΪ¾ÛºÏº¯Êý »ò ·Ö×é×Ö¶Î

select u.university,count(q.question_id)/count(distinct q.device_id) from user_profile u,question_practice_detail q where u.device_id=q.device_id grou