All of the above is not to say we won’t continue to make progress or there isn’t still work to be done in this important field. In fact, I see at least four areas, somewhat interrelated, where developments are either under way or are needed: implementation, foundations, higher level abstractions, and higher level interfaces.
In some ways the message of this book can be summed up very simply:
Let’s implement the relational model!
To elaborate: First of all, I think it’s clear from the body of the book that it’s being extremely charitable to SQL to describe it as a relational language. It follows that SQL products can be considered relational only to a first approximation. The truth is, the relational model has never been properly implemented in commercial form (at least, not in any mainstream product), and users have never really enjoyed the benefits that a truly relational product would bring. Indeed, that’s one of the reasons why I wrote this book, and it’s also one of the reasons why Hugh Darwen and I have been working for so long on The Third Manifesto. The Third Manifesto—the Manifesto for short—is a formal proposal for a solid foundation for future DBMSs. And it goes without saying that what it really does, in as careful and precise a manner as the authors are capable of, is define the relational model and spell out some of the implications of that definition. (It also goes into a great deal of detail on the impact of type theory on that ...