sum函式在SQL Server 2005中，添加了 over(partition by )的功能。

在2012、1014中添加了 over(partition by  order by )的功能，以及rows/range功能。

下面是具體的例子：

if object_id('test') is not null
   drop table test
go

create table test
(
id int  primary key,
name varchar(20),
groupname varchar(20)
)

insert into test
values(1,'小明','開發部'),
      (4,'小張','開發部'),
      (5,'小白','開發部'),

      (8,'小王','財務部'),
      (9, null,'財務部'),
      (15,'小劉','財務部'),

	  (16,'小高','行政部'),
      (18,'小王','行政部'),
	  (23,'小李','行政部'),
	  (29,'小吳','行政部');
 

select *,
       sum(id) over(partition by groupname ) 每個組的id之和,

	   sum(id) over(partition by groupname order by id) 每個組的id之和,

	   sum(id) over(order by id)  id之和
from test 

select *,

       sum(id) over(partition by groupname 
	                    order by id 
						rows between current row and unbounded following) 當前行_最後1行,

       sum(id) over(partition by groupname 
	                    order by id 
						rows between unbounded preceding and current row) 第1行_當前行
from test