题解 | #统计复旦用户8月练题情况#

select a.device_id,university,
sum(case when question_id is null then 0 else 1 end ),
sum(case when result like '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 university ='复旦大学' and (month(date)=8 or date is null)
group by a.device_id,university