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
一群渣渣,这才是正确的写法 select a.device_id, university, count(question_id) as question_cnt, sum(if(b.result = 'right',1,0)) as right_question_cnt from user_profile a left join question_practice_detail b on a.device_id = b.device_id and month(date)=8 group by a.device_id,university having university = "复旦大学"