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 university,difficult_level ,round(count(b.question_id)/count(distinct b.device_id),4) as avg_answer_cnt from user_profile as a join question_practice_detail as b on a.device_id=b.device_id join question_detail as c on b.question_id=c.question_id group by university,difficult_level