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
http://www.nowcoder.com/practice/88aa923a9a674253b861a8fa56bac8e5
SELECT up.university university, COUNT(qpd.question_id) / COUNT(DISTINCT qpd.device_id) avg_answer_cnt FROM question_practice_detail qpd INNER JOIN user_profile up ON qpd.device_id = up.device_id GROUP BY up.university ;
