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 university,difficult_level,round(count(qpd.question_id)/count(distinct u.device_id),4) as avg_answer_cnt from question_detail as q join question_practice_detail as qpd on q.question_id = qpd.question_id join user_profile as u on qpd.device_id = u.device_id where university = '山东大学' group by difficult_level
思路清晰
