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 a.university, FORMAT(COUNT(b.result)/COUNT(DISTINCT(b.device_id)),4) AS avg_answer_cnt FROM user_profile a,question_practice_detail b WHERE a.device_id=b.device_id GROUP BY a.university ORDER BY a.university