Theory and Practice of Relational Databases

The aim of this textbook is to provide the tutorial features - the guidance for students, complete clarification and examples, and to provide them in a practical way. Every concept, formula, and operation are given precise definitions that cover both the form and the meaning. Also, whenever appropriate, a behavioural description is given. In recognition of some difficulties in dealing with abstract concepts numerous examples are presented. Similarly, whenever a theorem is presented a full proof follows and, if possible, the subsequent steps in proving are illustrated by example. The examples play a particular role in this book. Almost every chapter contains essentially the following categories: "explanatory examples" (helping to acquire and to understand the topics being introduced), "solved problems" (showing how to apply the information from a section of the current chapter or using the information from the whole chapter) and "exercises" (to encourage readers to solve these by themselves). Solutions and explanations are given for almost all of the problems presented in the book. The examples are selected so to ensure that solutions can be as objective as possible, and are not dependant on a specific view of a system designer. This book does not pretend to cover all aspects of relational theory, but concentrates on some systematic treatment of database design problems. The languages to communicate with a database are then presented as well defined formal systems, the systems on which possible standards (such as SQL) can be based - not the other way round. No specific knowledge of computing by the reader is assumed, though familiarity with its fundamental concepts (such as field, record, file, procedure, transaction) would be helpful. Similarly, some understading of basic notions of mathematical logic and set theory is required, though all the necessary facts are compiled in an appendix.