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(`qpd`.`device_id`)/count(distinct `up`.`device_id`),4) from `question_practice_detail` as `qpd` join `user_profile` as `up` on `qpd`.`device_id` = `up`.`device_id` group by `university`;