MYSQL自定义函数判断是否正整数的实例代码

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