题解 | #浙大不同难度题目的正确率#

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