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 as u inner join question_practice_detail as qpd on u.device_id=qpd.device_id inner join question_detail as qd on qpd.question_id=qd.question_id where university='山东大学' group by difficult_level;
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