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
https://www.nowcoder.com/practice/d8a4f7b1ded04948b5435a45f03ead8c
select a.difficult_level,sum(if(a.result='right',1,0))/count(a.question_id) as correct_rate from (select user_profile.device_id,question_practice_detail.question_id,university,difficult_level,result from user_profile,question_detail,question_practice_detail where user_profile.device_id=question_practice_detail.device_id and question_practice_detail.question_id=question_detail.question_id and university='浙江大学')a group by difficult_level order by correct_rate
