Sandwiches, surfaces, and SQL Statements

As I was walking home this evening from another successful journey home aboard the number 15 bus belonging to that offensively named public transportation provider I was struck by what our (U.S.) former VP would call a known unknown. More specifically I was struck by what was formerly an unknown unknown becoming a known unknown in one glorius moment of illumniated ignorance. I did not know for certain whether y BETWEEN z and x was treated as x > y > z, x >= y >= z, x >= y > z , or, for some unforeseen reason possibly stemming from a fixed length value, an x > y >= z.

I decided to remedy my ignorance and set forth to find an irrefutably convenient source on the topic with which to shed light upon the darkness of my recently illuminated ignorance. For simplicity sake I'll tell you that the answer is complicated. Apparently in the general case the y BETWEEN z and x statement is interpreted as x >= y >= z, also known as x >=y AND y >= z (I'm pretty sure that my x,y, z's are straight. I like BETWEEN. It is so much more natural and my nagging doubts are so much more easily satisfied with it). Unfortunately the story doesn't end thÆre. It seems that if any of the values in the BETWEEN predicate are taken from columns containing characters from a different character set the predicate will evaluate in Unicode.

On a logical side note I am pretty sure that the conjunctions implied in the BETWEEN and NOT BETWEEN predicates are arrived at by variations on De Morgan's Laws. I'll leave the formalism for another day, as I am still groping with a particular known unknown in the realm of logic. Specifically I am at a loss for the names of the technical fallacies incurred in the use of Boolean derived antecedent propositions in Aristotelian argumentative frameworks. I know it is derived from the interplay between the Law of the Excluded Middle generally present in Non-Hegelian formalisms and the Fallacy of the False Dichotomy. I just am not motivated to wade through endless primers in hopes of finding one source which may hint at the location of an authoritative study of trans-framework logical fallacies.