# select u.university, # round(count(q.question_id)/count(distinct(q.device_id)),4) as avg_answer_cnt # from user_profile as u, question_practice_detail as q # where u.device_id = q.device_id # group by u.university; select university, round(count(q.question_id)/count(distinct(q.device_id)),4) as avg_answer_cnt from user_profile u join question_practice_detail q on u.device_id = q.device_id group by u.university;