This book presents a unified collection of concepts, tools, and
techniques that constitute the most important technology available today
for the design and implementation of information systems. The framework
adopted for this integration goal is the one offered by the relational
model of data, its applica- tions, and implementations in multiuser and
distributed environments. The topics presented in the book include
conceptual modeling of application environments using the relational
model, formal properties of that model, and tools such as relational
languages which go with it, techniques for the logical and physical
design of relational database systems and their imple- mentations. The
book attempts to develop an integrated methodology for addressing all
these issues on the basis of the relational approach and various
research and practical developments related to that approach. This book
is the only one available today that presents such an inte- gration. The
diversity of approaches to data models, to logical and physical database
design, to database application programming, and to use and imple-
mentation of database systems calls for a common framework for all of
them. It has become difficult to study modern database technology with-
out such a unified approach to a diversity of results developed during
the vigorous growth of the database area in recent years, let alone to
teach a course on the subject.