题解 | #统计每个学校各难度的用户平均刷题数#
统计每个学校各难度的用户平均刷题数
https://www.nowcoder.com/practice/5400df085a034f88b2e17941ab338ee8
select
university,
difficult_level,
round(
count(qu.question_id) / count(distinct qu.device_id),4) as avg_answer_cnt
from
user_profile as us,
question_practice_detail as qu,
question_detail as de
where
us.device_id in (
select
qu.device_id
from
question_detail
where
qu.question_id in (select de.question_id from question_detail ))
group by
university,
difficult_level;
发现答案基本都用了表连接，我想尝试一下用多次条件语句进行查询，不知道大佬们有何见解
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