Inside Symbian SQL: A Mobile Developer's Guide to SQLite

Chapter 3. The Relational Model

This chapter is an essential read if you are looking for a deeper understanding of common database theory, and explains concepts such as keys, views, referential integrity, normal forms and normalization. You don't have to read this chapter in order to understand SQL; it merely provides a theoretical and historical backdrop and is an appetizer to Chapter 4, which covers SQL in great detail and is specifically targeted at SQLite. This chapter presents only the minimal theoretical basis needed to get a good understanding and appreciation of the origin, aims, and means of SQL. It presents the theoretical roots of SQL, and examines its power and elegance. The aim is to prepare you to deal with SQL, not in isolation, but in the context of the relational model. If nothing else, it should give you an appreciation for how elegant, powerful, and complex a beast a relational database really is. You may be surprised by what even the most rudimentary relational databases are capable of.

SQL has a very practical exterior but a very theoretical interior. That interior is the relational model. The relational model came before SQL and created a need for SQL. The power of SQL lies not in the language itself but in the concepts set forth in the relational model. These concepts form the basis of SQL's design and operation.

The relational model is a powerful and elegant idea that has pervaded not only computer science but our daily lives as well, whether we know it or ...