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 u.university,qd.difficult_level,count(qpd.question_id)/count(distinct qpd.device_id) avg_answer_cnt from question_practice_detail qpd inner join question_detail qd on qd.question_id=qpd.question_id inner join user_profile u on u.device_id=qpd.device_id and u.university="山东大学" group by qd.difficult_level;
