窗口函数--over (partiton by order by)

下面把student表添加省份的字段，然后使用partition 按省份内学生成绩排名

alter table student add province nvarchar(20);
go
update top (6) student set province='JiangSu';
go
update student set province='ShangHai' where province is null;
go
select * from student;

select ROW_NUMBER() over (partition by province order by score desc) as 排名,
       name,
       score,
       province
from student

上图就是结果，JiangSu的6个人，排名就就到6；二ShangHai的7个人排名就到7。

当然Row_number()还可以替换成rank(),dense_rank()。