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 d.difficult_level,sum(if(q.result='right',1,0))/count(result) as correct_rate
from question_practice_detail q left join user_profile u on q.device_id = u.device_id left join question_detail d on
q.question_id = d.question_id
where u.university = '浙江大学'
group by d.difficult_level
order by correct_rate
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