varchar类型转换

CREATE function Ip2Float (@aIp varchar(30))
RETURNS float --将float(8) 改成float
AS
BEGIN

declare @ip varchar(30)
select @ip=@aIp
declare @Index int
declare @Part varchar(6)
declare @Rec float
select @Rec=0
select @Index=CHARINDEX( '. ',@ip)

WHILE (@Index > 0)
begin
select @Part=substring(@ip,1,@Index-1)
select @Rec=@Rec*1000+cast(@Part as float(8))
select @Ip=substring(@ip,@Index+1,len(@ip)-@Index)
select @Index=CHARINDEX( '. ',@ip)
-- select @Index 此句多余
end

select @Rec=@Rec*1000+cast(@Ip as float(8))
return(@Rec)
end