SQL1到n的累加

alter function liejia
( 
    @a int,
    @z int)
returns int
as
begin
   declare @sum int
   while(@a<=@z)
   begin
     set @sum=isnull(@sum,0)+@a
     set @a=ISNULL(@a,0)+1
   end
   return @sum
 end
go
select dbo.liejia(1,100)