Sql 如何根据另一个属性'；s值多少？

我有一个三栏的表格，分别是“年”、“学生人数”和“教员”。 我想知道每一个不同的教师的最大“学生数”是多少

该表如下所示：

year| students_count| faculty
------------------------------------
2001| 50            | Business
2002| 60            | Business
2003| 40            | Business
2001| 20            | Engineering
2002| 10            | Engineering
2003| 50            | Law

（不起作用）

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如果您每年需要，需要分组，并且教员人数最多

SELECT year,max(students_count),faculty FROM table group by year,faculty

但是，如果您只需要功能，那么您可以使用相关子查询

select top (1) with ties t.*
from table_name t
order by row_number() over (partition by faculty order by students_count   desc)

使用

行编号（）

您想要

densite\u rank（）

：

这将有助于：

select * from (select *,rank() over (partition by faculty order by sytudents_count desc 
) rnk form tablename) where rnk=1;

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为此，我认为您只需要在sql中使用GROUPBY。 这也许可以解决这个问题

Create Table School(
Year Number(4),
Students_Count Number(2),
Faculty Varchar2(20)
);

Insert Into School  Values (2001,50,'Business');
Insert Into School  Values (2002,60,'Business');
Insert Into School  Values (2003,40,'Business');
Insert Into School  Values (2001,20,'Engineering');
Insert Into School  Values (2002,10,'Engineering');
Insert Into School  Values (2003,50,'Law');

Select * From School;

Select  Faculty,Max(Students_Count) From School
Group By Faculty;

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您必须按每个组的字段进行分组以进行汇总。

select * from
(
select *,row_number() over(partition by faculty order by students_count desc) as rn
from tablename 
)A where rn=1

select t.*
from (select t.*,
             dense_Rank() over (partition by faculty order by students_count desc) as seq
      from table t
     ) t
where seq = 1;

select * from (select *,rank() over (partition by faculty order by sytudents_count desc 
) rnk form tablename) where rnk=1;

Create Table School(
Year Number(4),
Students_Count Number(2),
Faculty Varchar2(20)
);

Insert Into School  Values (2001,50,'Business');
Insert Into School  Values (2002,60,'Business');
Insert Into School  Values (2003,40,'Business');
Insert Into School  Values (2001,20,'Engineering');
Insert Into School  Values (2002,10,'Engineering');
Insert Into School  Values (2003,50,'Law');

Select * From School;

Select  Faculty,Max(Students_Count) From School
Group By Faculty;