This book presents an overview of the most fundamental aspects of the theory that underlies the Relational Database Model. As such it is self-contained though experience with formal models and abstract data manipulating on the one hand and with the practical use of a relational system on the other hand can help the reader. Such experience will offer the reader a better understanding of and a motivation for the different concepts, theories and results mentioned in the book. We have focussed on the most basic concepts and aspects of the relational model, without trying to give a complete overview of the state of the art of database theory. Recently a lot of books on databases in general and on the relational model in particular have been published. Most of them describe the use of database systems. 'Some clarify how information has to be structured and organized before it can be used to build applications. Others help the user in writing down his applications or in finding tricky ways to optimize the running time or the necessary space. Another category of books treat more fundamental and more general aspects such as the description of the relational model, independent of any implementation, the decomposition in normal forms or the global design of distributed databases. Few, however, are the books that describe in a formal way some of the subjects mentioned above.

Inhalt

1 Relational Database Model.- 1.1 Relation Schemes.- 1.2 Relation Instances.- 1.3 Database Schemes and Database Instances.- 1.4 Dynamic Schemes and Evolutions.- 1.5 Classification of Constraints.- 1.6 Example.- 1.7 Exercises.- 2 Query Systems.- 2.1 The Relational Algebra.- 2.1.1 Informal Description.- 2.1.2 Syntax of the Relational Algebra.- 2.1.3 Generating Part of the Relational Algebra.- 2.1.4 Views Represented by the Relational Algebra.- 2.1.5 Expressive Power of the Generating Part.- 2.2 The Tuple Calculus.- 2.2.1 Informal Description.- 2.2.2 Syntax of the Tuple Calculus.- 2.2.3 Generating Part of the Tuple Calculus.- 2.2.4 Views Represented by the Tuple Calculus.- 2.2.5 Expressive Power of the Generating Part.- 2.3 SQL: Structured Query Language.- 2.3.1 Informal Description.- 2.3.2 Syntax of SQL.- 2.3.3 Generating Part of SQL.- 2.3.4 Views Represented by SQL.- 2.3.5 Expressive Power of the Generating Part.- 2.4 Reduction of the Tuple Calculus to the Algebra.- 2.4.1 Method.- 2.4.2 Example.- 2.5 Reduction of the Algebra to SQL.- 2.5.1 Method.- 2.5.2 Example.- 2.6 Reduction of SQL to the Tuple Calculus.- 2.6.1 Method.- 2.6.2 Example.- 2.7 Exercises.- 3 Constraints.- 3.1 Some Terminology.- 3.2 Functional Dependencies.- 3.3 Multivalued Dependencies.- 3.4 Join Dependencies.- 3.5 Inclusion Dependencies.- 3.6 Tuple and Equality Generating Dependencies.- 3.7 Exercises.- 4 Vertical Decompositions.- 4.1 First Normal Form.- 4.2 Second and Third Normal Form.- 4.3 Boyce-Codd Normal Form.- 4.4 Constraint Preserving Normalization.- 4.5 Fourth and Fifth Normal Form.- 4.6 Vertical Decomposition and Consistency Checking.- 4.7 Exercises.- 5 Horizontal Decompositions.- 5.1 Horizontal Decompositions.- 5.2 The Membership and Inference Problem for Fds and Ads.- 5.3 The Inheritance of Dependencies.- 5.4 Normal Forms for Horizontal Decompositions.- 5.5 Exercises.- 6 Incomplete Information.- 6.1 Representation Systems for Existing-but-Unknown Nulls.- 6.2 Updating Relations with Existing-but-Unknown Nulls.- 6.3 Constraints in Incomplete Databases.- 6.4 Relations with No-Information Nulls.- 6.5 The Weak Instance Model.- 6.6 Exercises.- 7 The Nested Relational Database Model.- 7.1 Nested Relation Schemes and Instances.- 7.2 The Nested Relational Algebra.- 7.3 Constraints.- 7.4 The Expressiveness of the Nested Relational Algebra.- 7.5 Hierarchical Instances.- 7.6 Exercises.- 8 Updates.- 8.1 Transactions.- 8.2 Equivalent Transactions.- 8.3 Dynamic Relation Constraints.- 8.4 Axiomatization of Equivalence of Transactions.- 8.5 Exercises.