CREATE FUNCTION [dbo].[svf_NonNegativeInteger] (
  @val NVARCHAR(4000)
) RETURNS BIT
AS
BEGIN
   DECLARE
    @rtv BIT = 1
 
   SET @val = ISNULL(LTRIM(RTRIM(@val)), N'-')
   IF @val LIKE '%[^0-9]%' OR @val = N''
      SET @rtv = 0
   ELSE
      SET @rtv = 1
 
   RETURN @rtv
END