题解 | #统计复旦用户8月练题情况#

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"