CREATE FUNCTION fnNextSortOrder(@Seed datetime = '1/1/2001')
RETURNS bigint
AS BEGIN

DECLARE @Val bigint

SET @Val = (year(@Seed)*10000000000) + 
            (month(@Seed)*100000000) +
            (day(@Seed)*1000000)+
            (datepart("hh",@Seed)*10000)+
            (datepart("mm",@Seed)*100)+
            (datepart("ss",@Seed))*100

RETURN @Val
END
GO