题解 | #统计每个学校各难度的用户平均刷题数#
统计每个学校各难度的用户平均刷题数
https://www.nowcoder.com/practice/5400df085a034f88b2e17941ab338ee8
select university,difficult_level,round(count(q.question_id)/count(distinct(q.device_id)),4) as avg_answer_cnt from user_profile u left join question_practice_detail q on u.device_id=q.device_id right join question_detail q1 on q1.question_id=q.question_id group by university, difficult_level
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