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 a.device_id, a.university, count(b.question_id) as question_cnt, sum(case when b.result = "right" then 1 else 0 end) as right_question_cnt FROM user_profile as a left join question_practice_detail as b on a.device_id = b.device_id WHERE a.university = "复旦大学" AND (MONTH(b.date)=08 or b.date is null) group by a.device_id;