题解 | #浙大不同难度题目的正确率#
浙大不同难度题目的正确率
http://www.nowcoder.com/practice/d8a4f7b1ded04948b5435a45f03ead8c
select *
from
(select q2.difficult_level,
sum(if (q1.result='right',1,0))/count(q1.question_id) as correct_rate
from user_profile u
inner join question_practice_detail q1
on u.device_id=q1.device_id
inner join question_detail q2
on q1.question_id=q2.question_id
where u.university='浙江大学'
group by q2.difficult_level)a
order by a.correct_rate;
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