Re: Implementation of boolean types.

>> I have to say that I buy into Date's viewpoint: relations are predicates, and attributes are the variables of the predicate. <<

I am more inclined toward thinking if them as facts. Facts are always "true" in the sense of existing. You do not talk about substitution in a set.

Predicates can be true or false (or whatever other logical values your deductive system has). As Dave McGovran points out, SQL has no rule of inference, so it is not a logical system. We even call them <search conditions> and not predicates. Received on Fri Jul 15 2005 - 10:55:09 CDT