字串IP地址轉換成IP數值函數

if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[f_IP2Int]') and xtype in (N'FN', N'IF', N'TF'))
drop function [dbo].[f_IP2Int]
GO

--1. 字串IP地址轉換成IP數值函數。
CREATE FUNCTION dbo.f_IP2Int(
@ip char(15)
)RETURNS bigint
AS
BEGIN
DECLARE @re bigint
SET @re=0
SELECT @re=@re+LEFT(@ip,CHARINDEX('.',@ip+'.')-1)*ID
,@ip=STUFF(@ip,1,CHARINDEX('.',@ip+'.'),'')
FROM(
SELECT ID=CAST(16777216 as bigint)
UNION ALL SELECT 65536
UNION ALL SELECT 256
UNION ALL SELECT 1)a
RETURN(@re)
END
GO