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 up.device_id,up.university, count(qpd.question_id) as question_cnt, sum(if(qpd.result='right',1,0)) as right_question_cut from user_profile as up left join question_practice_detail as qpd on up.device_id = qpd.device_id and month(qpd.date)=8 where up.university ='复旦大学' group by up.device_id
新get一个知识点，sum里面可以套用if，也可以用if函数的快速模式来写
