Sorting by age issue.

I have a table that stores users birthdays, date, month year, etc.

I then have a function which turns these into an age, I.E. 24.

Problem is when I want to show all users who are a specific age I get stuck. I can do it an easy way and sort by their year born, but this will sometimes show a fluctuation because everyone born from 1988 may not be 20 yet.

Is there any work around for this?

Sure, it just requires a slightly more complicated SQL statement that converts the date or datetime field to a Unix timestamp. I would probably do something like this:
...where tblTableName is the table and fldBirthDate is the field containing your birthdates.

A Unix timestamp is the number of seconds since Jan. 1, 1970. 31556926 is the number of seconds in 1 year (365.24 days).

I haven't tested this explicitly, so no guarantees, but I think it gets the general idea across. And I'm sure there may be a more eloquent way to do this, so if anybody knows one, please share!