选择相对于sql中其他列值多出50％的列值

Question

我需要编写一个SQL查询（SQL Server）。

我有一张看起来像这样的桌子。 表名：类

np.mean (with the axis parameter)
np.std  (with the axis parameter)
np.roll (again with the axis parameter)
np.mgrid
np.max  (again with axis parameter)

依旧......

我想显示包含所有列的表格，但是对于主题列，找到学生姓名的出现率为50％或更高

例如，如果学生姓名 - ＆＃39;詹姆斯＆＃39;对于2名4名受试者，则应显示他的名字，并且应排除其他符合50％标准的人。

由于

Answer 1

使用......

select Student
from Class
group by Student
having count(Student) >= (select count(distinct [Subject]) from Class) / 2.0

或者如果你喜欢变量......

declare @numOfSubjects int = (select count(distinct [Subject]) from Class)

select Student
from Class
group by Student
having count(Student) >= @numOfSubjects / 2.0

要将所有列都带回CTE

with cte as(
    select Student
    from Class
    group by Student
    having count(Student) >= (select count(distinct [Subject]) from Class)) / 2.0)

select 
    c.*
from Class c
inner join cte on cte.Student = c.Student

Answer 2

只需获取所有列......

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