SQL and Relational Theory, 2nd Edition

CONCLUDING REMARKS

It’s my strong belief that database professionals in general, and SQL practitioners in particular, should have some familiarity with the basic concepts of predicate logic (or relational calculus—it comes to the same thing). I’d like to conclude by trying to justify this position.

My basic point is simply that a knowledge of logic helps you think precisely (and in our field, the importance of thinking precisely is surely paramount). In particular, it forces you to appreciate the significance of proper quantification. Natural language is so often imprecise; however, careful consideration of what quantifiers are needed allows you to pin down the meaning of what can otherwise be very imprecise natural language statements. By way of example, you might like to meditate on exactly what Abraham Lincoln meant—or might have meant, or thought he might have meant, or might have thought he meant—when he famously said: “You can fool some of the people some of the time, and some of the people all the time, but you cannot fool all the people all of the time.”

Now, I’m well aware there are many who disagree with me here; that is, there are many who feel ordinary mortals shouldn’t have to grapple with a subject as abstruse as logic seems to be. In effect, they claim that logic is just too difficult for most people to deal with. Now, that claim might be true in general (logic is a big subject). But you don’t need to understand the whole of logic for the purpose at hand; in fact, I ...