题解 | 统计每个用户的平均刷题数
统计每个用户的平均刷题数
https://www.nowcoder.com/practice/f4714f7529404679b7f8909c96299ac4
select t1.university,t3.difficult_level,count(t2.question_id)/count(distinct t2.device_id) as avg_answer_cnt from user_profile as t1 inner join question_practice_detail as t2 on t1.device_id=t2.device_id and t1.university='山东大学' inner join question_detail as t3 on t2.question_id=t3.question_id group by university,difficult_level
而且一般说的也很宽泛 不是特指后端