题解 | 统计每个用户的平均刷题数
统计每个用户的平均刷题数
https://www.nowcoder.com/practice/f4714f7529404679b7f8909c96299ac4
select up.university, qd.difficult_level, round(count(qpd.question_id)/count(distinct qpd.device_id),4)as avg_answer_cnt from question_practice_detail qpd inner join user_profile up on qpd.device_id = up.device_id inner join question_detail qd on qpd.question_id = qd.question_id where up.university="山东大学" group by up.university,qd.difficult_level order by up.university,qd.difficult_level asc