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(right_result) / count(right_result) as correct_rate
from(
select difficult_level, case when result="right" then 1
else 0
end right_result
from user_profile as a
inner join question_practice_detail as b
on a.device_id=b.device_id
left join question_detail as c
on b.question_id = c.question_id
where university = "浙江大学"
) as d
group by difficult_level
order by correct_rate asc
