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 difficult_level, sum(if(result='right',1,0))/sum(if (result is not null,1,0)) as correct_rate from (select u.university, qpd.result, qd.difficult_level from user_profile u join question_practice_detail qpd on u.device_id=qpd.device_id join question_detail qd on qpd.question_id=qd.question_id where university='浙江大学') as t group by difficult_level order by correct_rate asc;