题解 | #统计复旦用户8月练题情况#

# 获取8月份用户
select a.device_id,
a.university,
count( question_id) as question_cnt,
sum(case when result = 'right' then 1 else 0 end ) as right_question_cnt
from user_profile a 
left join(
select *
from question_practice_detail  
where month(date) = '08') b on a.device_id = b.device_id
where a.university = '复旦大学'
GROUP BY a.device_id,
a.university