题解 | #浙大不同难度题目的正确率#

select 
difficult_level,
sum(if(result = 'right',1,0))/count(qd.difficult_level) correct_rate
from user_profile up
inner join  question_practice_detail qpd on up.device_id = qpd.device_id
inner join  question_detail qd on qpd.question_id = qd.question_id
where up.university = '浙江大学'
group by qd.difficult_level
order by correct_rate

# 现在运营想要了解浙江大学的用户在不同难度题目下答题的正确率情况