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,
    count(if (qpd.result = 'right', 1, null)) 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;