题解 | #浙大不同难度题目的正确率#

select qd.difficult_level as difficult_level, sum(if(qpd.result like 'right',1,0)) / count(qpd.device_id) as correct_rate from user_profile as up left join question_practice_detail as qpd on up.device_id=qpd.device_id left join question_detail as qd on qd.question_id=qpd.question_id

where up.university like '浙江大学' group by qd.difficult_level having qd.difficult_level !='None' order by correct_rate ;