题解 | #统计复旦用户8月练题情况#

没在表里看到日期相关的列。。。。。。还是看了解题思路才发现有个date

SELECT a.device_id
      ,a.university
      ,count(b.question_id ) question_cnt
      ,sum(case when b.result = 'right' then 1 else 0 end ) right_question_cnt
from user_profile a
left join question_practice_detail b
on a.device_id = b.device_id
where a.university = '复旦大学' and  MONTH(date) = 8
group by a.device_id,a.university