题解 | 统计每个学校的答过题的用户的平均答题数
统计每个学校的答过题的用户的平均答题数
https://www.nowcoder.com/practice/88aa923a9a674253b861a8fa56bac8e5
select university,round(count(question_id)/count(distinct(question_practice_detail.device_id)),4) as avg_answer_cnt from user_profile inner join question_practice_detail using(device_id) group by university order by 1
distinct还可以放在聚合函数中使用，这个没想到
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