题解 | #统计复旦用户8月练题情况#
统计复旦用户8月练题情况
http://www.nowcoder.com/practice/53235096538a456b9220fce120c062b3
select t1.device_id, university, count(t2.question_id) as question_cnt, sum( case when result = 'right' then 1 else 0 end ) as right_question_cnt from ( select device_id, university from user_profile where university = '复旦大学' ) t1 left join ( select * from question_practice_detail where month(date) = '8' ) t2 on t1.device_id = t2.device_id group by university, t1.device_id