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 e1.university, e3.difficult_level, count(e2.question_id)/count(distinct(e2.device_id)) as avg_answer_cnt from user_profile as e1 left join question_practice_detail as e2 on e1.device_id = e2.device_id left join question_detail as e3 on e2.question_id = e3.question_id group by university, difficult_level having avg_answer_cnt !='None' order by avg_answer_cnt desc
