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
d.difficult_level,
sum(if (c.result = "right", 1, 0)) / count(c.device_id) as correct_rate
# avg(if (c.result = "right", 1, 0)) as correct_rate
from
(
select
a.*
from
question_practice_detail a
left join user_profile b on a.device_id = b.device_id
where
b.university = "浙江大学"
) as c
left join question_detail as d on c.question_id = d.question_id
group by
d.difficult_level
order by
correct_rate
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