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
#浙江用户where university='浙江大学', #不同难度 group by difficult_level, #正确率 对的题数/总题数(count) Select difficult_level,sum(if(result='right',1,0))/count(*) as correct_rate from user_profile up left join question_practice_detail qpd on up.device_id =qpd.device_id right join question_detail qd #right join 的原因是,如果是left的话会有没有匹配上的none on qpd.question_id=qd.question_id where university='浙江大学' group by difficult_level order by correct_rate