declare @sql varchar(1000)
select @sql=isnull(@sql+',','')+aa from (select top 5 * from ab order by newid())a
update ab2 set aa=@sql where ......

------解决方案--------------------
declare @str varchar(200)
select @str = isnull(@str+',','')+aa from (select top 5 * from AB) bb
print @str
这样就可以查出你要的数据了

------解决方案--------------------
SQL code


    declare @s nvarchar(1000)
    select @s=isnull(@s+',','')+quotename(Name) from (select top 5 Name from 表名 order by newiD())t
    update 表名 set Name=@s where .......

------解决方案--------------------
SQL code

--环境
create table tb(id int identity(1,1),[name] char(10))
insert into tb select 'a'
insert into tb select 'b'
insert into tb select 'c'
insert into tb select 'd'
insert into tb select 'e'
insert into tb select 'f'
go
create table ttb(id int identity(1,1),[name] char(100))
select * from ttb
delete from ttb
go
--存储过程
create proc GetTop 
 as 
 begin 
  declare @Row int
  set @Row=0
  while @Row < 5
  begin 
  declare @sql nvarchar(200)
  set @sql=''
  select @sql=@sql+[name] from (select top 5 * from tb order by newid()) t
  insert ttb select name = @sql
  set @Row=@Row+1
  end
end

--删除环境
drop table ttb
go
drop table tb
go
drop proc GetTop

------解决方案--------------------
create table tb(id varchar(10),username varchar(10))
insert into tb values('1',      '123')
insert into tb values('2',      '234')
insert into tb values('3',      'hell')
go

declare @a varchar(5000),@b  varchar(5000)
select @a='',@b=''
select @a=@a+'，'+rtrim(id),@b=@b+'，'+username from tb
select 'id',stuff(@a,1,1,'') union select 'username',stuff(@b,1,1,'')  


drop table tb

/*
-------- --------------
id       1，2，3
username 123，234，hell

（所影响的行数为 2 行）
*/