题解 | #统计复旦用户8月练题情况#

SELECT A.device_id,A.university,
IF(B.question_cnt is null , 0, B.question_cnt),
IF(B.right_question_cnt is null , 0,B.right_question_cnt)
From user_profile A left join
(select device_id,count(device_id) as question_cnt,sum(Case result when 'wrong' then 0 else 1 end ) as right_question_cnt From question_practice_detail where month(date)=8 Group By device_id ) AS B
ON A.device_id=B.device_id
where university ='复旦大学'