题解 | #统计复旦用户8月练题情况#
统计复旦用户8月练题情况
https://www.nowcoder.com/practice/53235096538a456b9220fce120c062b3
select device_id,university,count(question_id),count(if(result='right',question_id,null)) from (select u.device_id,u.university,qp.question_id,qp.result,qp.date from user_profile u left join question_practice_detail qp on u.device_id = qp.device_id where u.university = '复旦大学' and (qp.date like '2021-08%' or date is null) ) t group by device_id,university
