If the date you want to compare is in the same format
as that you are pulling from the database, you might
be able to perform a SELECT statement on it and let
the database tell you which date is younger (or older).
This method requires a connection to a database,
and might not be the fastest way, but if you are designing
for portability, would require less packages be installed
than going whole hog and installing Date::Manip.
You could also just compare the dates manually. I.e:
($d,$m,$y) = split /-/, $date;
$dv1 = $d+31*$m+365*$y;
($d,$m,$y) = split /-/, $date_from_db;
$dv2 = $d+31*$m+365*$y;
if ($dv1 < $dv2) {
something;
...
...
done;
}