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, count(qpd.question_id)/count(distinct(qpd.device_id)) avg_answer_cnt from user_profile up join question_practice_detail qpd on up.device_id = qpd.device_id join question_detail qd on qpd.question_id = qd.question_id where up.university = '山东大学' group by qd.difficult_level
