题解 | #浙大不同难度题目的正确率#

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

题目：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，请取出相应数据，并按照准确率升序输出。

限制条件：浙江大学

分组：不同难度

展示对象：正确率：正确数/总答题数

考察：三表连接