ABSTRACT
The database is the foundation of a GIS. A knowledge of the fundamental principles of databases is necessary to understand GIS technology. Many existing GISs are built upon general-purpose relational databases; certainly all GISs will connect with such systems in a distributed environment. This chapter introduces the reader to the main principles of databases. The general database approach is introduced in section 2.1, along with the high-level architecture of a database system. The most common database model is the relational model, described in detail in section 2.2. Based on an understanding of the relational model, the principles of database development are introduced in section 2.3. The object-oriented model extends the relational model in a way that offers several particularly useful advantages for GIS. The object-oriented model and object-oriented database systems are described in section 2.4.
