Date/Time formatting function

CREATE FUNCTION fn_format (@fmt varchar(100)='YYYYMMDD HH:MI:SS.LL', @date datetime)  
RETURNS varchar(100) AS  
BEGIN 
DECLARE @datestring varchar(50), @i tinyint, @s char(1), @ss char(1), @s2 varchar(10)
SET @datestring = ''
SET @i = 1
SET @s = left(@fmt,1)
WHILE @i < DATALENGTH(@fmt)
BEGIN
SET @ss = Substring(@fmt,@i,1)
If @ss <> @s
BEGIN
SET @fmt = substring(@fmt,1,@i-1) + ''',''' + substring(@fmt,@i,DATALENGTH(@fmt))
SET @i = @i + 3
SET @s = @ss
END
SET @i = @i + 1
END
SET @fmt=''''+@fmt+''''
declare cur cursor read_only for select value from system.dbo.fn_split(@fmt,',')
open cur
FETCH NEXT FROM cur INTO @s2
WHILE (@@fetch_status <> -1)
BEGIN
IF (@@fetch_status <> -2)
BEGIN
IF @s2 = 'YY' SET @datestring = @datestring + right(cast(datepart(year,@date) as char(4)),2)
ELSE IF @s2 = 'YYYY' SET @datestring = @datestring + right(cast(datepart(year,@date) as char(4)),4)
ELSE IF @s2 = 'MM' SET @datestring = @datestring + right('0'+ltrim(str(datepart(month,@date))),2)
ELSE IF @s2 = 'DD' SET @datestring = @datestring + right('0'+ltrim(str(datepart(day,@date))),2)
ELSE IF @s2 = 'HH' SET @datestring = @datestring + right('0'+ltrim(str(datepart(hour,@date))),2)
ELSE IF @s2 = 'NN' SET @datestring = @datestring + right('0'+ltrim(str(datepart(minute,@date))),2)
ELSE IF @s2 = 'SS' SET @datestring = @datestring + right('0'+ltrim(str(datepart(second,@date))),2)
ELSE IF @s2 = 'LL' SET @datestring = @datestring + ltrim(str(datepart(millisecond,@date)))
ELSE   SET @datestring = @datestring + @s2
END
FETCH NEXT FROM cur INTO @s2
END
close cur
deallocate cur
RETURN (@datestring)
END