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 up.university ,qd.difficult_level ,count(qpd.question_id)/count(distinct qpd.device_id) as avg_answer_cnt from user_profile as up join question_practice_detail as qpd on up.device_id = qpd.device_id left join question_detail as qd on qpd.question_id = qd.question_id group by university , difficult_level
