题解 | #统计复旦用户8月练题情况#

select device_id,
       university,
       (select count(id)
        from (select qpd.id
              from question_practice_detail qpd
              where device_id = up.device_id
                and MONTH(date) = 8) var)     as question_cnt,
       (select count(*)
        from (select *
              from question_practice_detail as qpd
              where device_id = up.device_id
                and result = 'right') as var) as right_question_cnt
from user_profile up
where university = '复旦大学';