in reply to Bringing Logic Programming to Perl

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.