SQL and Relational Theory, 2nd Edition

A REVIEW OF THE ORIGINAL MODEL

The purpose of this section is to serve as a kickoff point for subsequent discussions; it reviews some of the most basic aspects of the relational model as originally defined. Note that qualifier—“as originally defined”! One widespread misconception about the relational model is that it’s a totally static thing. It’s not. It’s like mathematics in that respect: Mathematics too is not a static thing but changes over time. In fact, the relational model can itself be seen as a small branch of mathematics; as such, it evolves over time as new theorems are proved and new results discovered. What’s more, those new contributions can be made by anyone who’s competent to do so; like other branches of mathematics, the relational model, though originally invented by one man, has become a community effort and now belongs to the world.

By the way, in case you don’t know, that one man was E. F. Codd, at the time a researcher at IBM (E for Edgar and F for Frank—but he always signed with his initials; to his friends, among whom I was proud to count myself, he was Ted). It was late in 1968 that Codd, a mathematician by training, first realized that the discipline of mathematics could be used to inject some solid principles and rigor into a field, database management, that prior to that time was all too deficient in any such qualities. His original definition of the relational model appeared in an IBM Research Report in 1969, and I’ll have a little more to say about that ...