SQL 同一张表中相同字段的内容合并为一条记录(不同字段的那一列每个记录后面加逗号)

一、创建表
create table stuUnion
(
 sid int identity primary key,
 cid int,
 id varchar(500)
)

二、添加数据
insert into stuUnion
select 1,'a' union
select 1,'b' union
select 2,'c' union
select 2,'d' union
select 3,'e' union
select 3,'f' union
select 3,'g'

三、用标量函数查询
(1)创建标量函数
create function b(@cid int)
returns varchar(500)
as
begin
declare @s varchar(500)
select @s=isnull(@s+'','')+rtrim(id)+',' from stuUnion where cid=@cid
return @s
end;

(2)用标量函数查询
select cid,dbo.b(cid) as id from stuUnion group by cid

三、用sqlserver的xml
select cid,ID=STUFF((select ' '+rtrim(id)+',' from stuUnion where st.cid=cid order by id for XML path('')),1,1,'') from stuUnion st group by cid