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题解 | #计算25岁以上和以下的用户数量#

select age_cut,count(age_cut) as number from -- 子查询 (select *, (case when age<25 or age is null then'25岁以下' when age>=25 then'25岁及以上' end) as ag...

2023-02-15

1 201

题解 | #统计每个学校各难度的用户平均刷题数#

select university,difficult_level,count(b.question_id)/count(distinct b.device_id) from user_profile as a right join question_practice_detail as b on ...

2023-02-15

1 248