题解 | 统计复旦用户8月练题情况

select
up.device_id, up.university,
ifnull(count(qpd.question_id), 0) as question_cnt,
ifnull(sum(case result when 'right' then 1 else 0 end), 0) as right_question_cnt
from user_profile up
left join question_practice_detail 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, up.university;