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,count(q.question_id)/count(distinct q.device_id) AS avg_answer_cnt FROM user_profile AS a JOIN question_practice_detail AS q ON a.device_id=q.device_id GROUP BY a.university
这里一直有个小点卡住，就是把distinct q.device_id写成了distinct. q.device_id。注意distinct不用标点.
