sql 自定义函数-16进制转10进制

做过笔记，好记性不如烂笔头：

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

 SET QUOTED_IDENTIFIER ON
 GO
 SET ANSI_NULLS ON
 GO

 CREATE  function HEXTOINT(@hexstr varchar(10))
 returns bigint
 as
 begin
 if left(@hexstr,2) in ('0x','0X') set @hexstr=substring(@hexstr,3,10)
 declare @i int, @res bigint, @l int, @c char, @ascii0 int, @asciiF int
 select @i=1, @l=len(@hexstr), @res=0, @ascii0=ascii(''), @asciiF=ascii('F')
 if @hexstr is null OR @l=0 return null
 while @i<=@l begin
    set @c=upper(substring(@hexstr,@i,1))
    if not ascii(@c) between @ascii0 and @asciiF return(null)
    set @res=@res+cast(1.0 as bigint)*case when isnumeric(@c)=1 then
 cast(@c as int) else ascii(@c)-55 end*power(16,@l-@i)
    set @i=@i+1
 end
 return(@res)
 end

 GO
 SET QUOTED_IDENTIFIER OFF
 GO
 SET ANSI_NULLS ON
 GO