DateTime to hh:mm:ss

CREATE FUNCTION BP_Select_HHMMSS(@DateTime DATETIME)
RETURNS VARCHAR(50)
AS
BEGIN

DECLARE @RetVal VARCHAR(50)

DECLARE @hh varchar(3),@mi varchar(3),@ss varchar(3)
select @hh=datepart(hh,@DateTime)
select @mi=datepart(mi,@DateTime)
select @ss=datepart(ss,@DateTime)
if(len(@hh)<2)
set @hh='0'+@hh
if(len(@mi)<2)
set @mi='0'+@mi
if(len(@ss)<2)
set @ss='0'+@ss
select @RetVal= @hh + ':'+ @mi + ':' + @ss


RETURN(@RetVal)
END