题解 | #统计每个学校各难度的用户平均刷题数#
统计每个学校各难度的用户平均刷题数
https://www.nowcoder.com/practice/5400df085a034f88b2e17941ab338ee8
select u.university,q2.difficult_level,(count(q1.question_id)/count(distinct(q1.device_id))) as avg_answer from user_profile as u inner join question_practice_detail as q1 on u.device_id = q1.device_id inner join question_detail as q2 on q1.question_id=q2.question_id group by u.university, q2.difficult_level