If, with my limited knowledge of Prolog, I do understand it well, the way of working with Prolog is to write a set of rules (a program), load it, and then query it. Would it be possible to mix the phases - that is adding rules with quering the whole set? With that Prolog systems could be used as data base. With SQL you can mix modifying of data and quering it.
At the current time, no you can't do that. You would have to recreate the the set of rules and reload them. However, AI::Prolog is now on its way to the CPAN so you will soon be able to download it and see for yourself.