> If you are really using Prolog professionally, then typically Prolog is the database. You simply assert facts, and retrieve them by querying the built-in Prolog database.

That was my personal aha moment with Prolog when I realised that Prolog statements are quite similar to SQL queries in that you declaratively define the results you expect instead of the exact directions describing how to arrive at those results.

It's a very powerful and elegant concept.