Today, if you have a well-designed database management system, you have the keys to the kingdom of data processing and decision support. That is why there now exists a prototype machine whose complete design is based on the relational model. Its arithmetic hardware is a quite minor part of thearchitecture. In fact, the old term "computer system" now seems like a misnomer.
My first paper dealing with the application of relations (in the mathematical sense) to database management was a non-confidential IBM research report made available to the general public that was entitled Derivability, Redundancy, and Consistency of Relations stored in Large Data Banks [Codd 1969]. I placed a great deal of emphasis then on the preservation of integrity in a commercial database, and I do so now. In this book, I devote Chapters 13 and 14 exclusively to that subject.
Another concern of mine has been, and continues to be, precision. A database management system (DBMS) is a reasonably complex system, even if unnecessary complexity is completely avoided. The relational model intentionally does not specify how a DBMS should be built, but it does specify what should be built, and for that it provides a precise specification.
An important adjunct to precision is a sound theoretical foundation. The relational model is solidly based on two parts of mathematics: firstorder predicate logic and the theory of relations. This book, however, does not dwell on the theoretical foundations, but rather on all the features of the relational model that I now perceive as important for database users, and therefore for DBMS vendors. My perceptions result from 20 years of practical experience in computing and data processing (chiefly, but not exclusively, with large-scale customers of IBM), followed by another 20 years of research.
I believe that this is the first book to deal exclusively with the relational approach. It does, however, include design principles in Chapters 21 and 22. It is also the first book on the relational model by the originator of that model. All the ideas in the relational model described in this book are mine, except in cases where I explicitly credit someone else.