题解 | #浙大不同难度题目的正确率#

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

left join question_detail as qd
on qpd.question_id = qd.question_id

where up.university = "浙江大学"
group by qd.difficult_level
order by correct_rate

主要注意部分是正确率，用正确数/答题数即可

sum(if(qpd.result="right",1,0))/count(qpd.question_id) as correct_rate

限定条件：题目难度分组