In this chapter, we've examined the structure of databases in terms of the normalization process. The basic principle underlying normalization is the elimination of redundancy by way of lossless decompositionthe ability to split relations apart without losing information. This principle is formalized in the concept of normal forms. The first three normal forms, which are the ones most commonly applied, are encapsulated in the jingle "The key, the whole key, and nothing but the key, so help me Codd." The remaining three normal forms are used only in exceptional cases.
In the next chapter, we'll examine how relations are logically linked when we explore the modeling of the relationships between entities.