题解 | #统计复旦用户8月练题情况#

select u.device_id, u.university, 
count(if(month(q.date) = 8, q.device_id, null)) as question_cnt, 
count(if(q.result = 'right', q.result, null)) as right_question_cnt
from user_profile u left join question_practice_detail q
on u.device_id = q.device_id
where u.university = '复旦大学'
group by u.device_id