题解 | #统计复旦用户8月练题情况#

select user_profile.device_id, user_profile.university, COUNT(question_id) question_cnt, sum(if(question_practice_detail.result='right',1,0)) right_question_cnt
from user_profile left join question_practice_detail on user_profile.device_id=question_practice_detail.device_id
where user_profile.university='复旦大学' and month(question_practice_detail.date)=8 
group by user_profile.device_id