题解 | #浙江大学用户题目回答情况#
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
#答题总数量
select count(question_id) from question_practice_detail
#用户id
select count(distinct device_id) from user_profile
最终结果: select p.university,count(d.question_id) / count(distinct p.device_id) from user_profile p join question_practice_detail d on p.device_id = d.device_id group by p.university
查看7道真题和解析