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