[kh99]

Well, you might be able to do it the same way that birthdays are done. That is, the birth date is stored then age is calculated using the current date and birth date. You don't have to use real dates for the "current" date. In fact if you're working with the same months as in real life you could probably fake the years if you wanted by adding/subtracting some constant before doing the calculations (otherwise the year will have to be between 1970 and 2034 for the date functions to work).