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( case when result = 'right' then 1 else 0 end ) / count(1) as correct_rate from ( select t2.difficult_level, t1.result from ( select device_id, question_id, result from question_practice_detail where device_id in ( select device_id from user_profile where university = '浙江大学' ) ) t1 join ( select question_id, difficult_level from question_detail ) t2 on t1.question_id = t2.question_id ) t group by difficult_level order by correct_rate;#一步一步分析,然后组合代码#