题解 | #统计复旦用户8月练题情况#

select
us.device_id
,us.university
,count(qu.question_id)
,sum(if(qu.result='right',1,0))
from
user_profile as us
left join
question_practice_detail as qu
on
us.device_id = qu.device_id	
where 
us.university = '复旦大学'
and (month(date) = 8 or date is null)
group by
us.device_id