取一个表的前m-n个字段(用函数)

---create by talantlee
---4/19/05
---取一个表的前m-n个字段
--
--declare @a varchar(800)
--set @a=dbo.select_ncolumn('student',1,1000)--,癬﹍挡
--exec('select '+@a +' from student')---猔種
create  function select_ncolumn(@tname varchar(100),@m int,@n int)
returns varchar(800)
as
begin
declare @string varchar(500)
declare  @i int,@maxcount int
set @i =@m
set @string =''
select @maxcount=count(*) from syscolumns where id=object_id(@tname
if(@maxcount<@n)
set @n=@maxcount-
while (@i<=@n)
begin
select @string=@string+','+name  from syscolumns where id=object_id(@tname) and colorder= @i
--┮Τ
set @i=@i+1
end
set @string=stuff(@string,1,1,'')

return @string
end