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 u.device_id,u.university,count(pq.question_id) question_cnt,sum(if(pq.result='right',1,0)) from (select device_id,university from user_profile where university='复旦大学') u left join question_practice_detail pq on u.device_id=pq.device_id and month(pq.date)=08 group by u.device_id;
sum(if(pq.result='right',1,0))求和
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