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, COUNT(qpd.question_id) / COUNT(DISTINCT(qpd.device_id)) as 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 order by avg_answer_cnt desc;
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