A database is a structured collection of data. Databases provide multiple benefits over data stored in a flat file format, such as shapefile or KML. The benefits include complex queries, complex relationships, scalability, security, data integrity, and transactions, to name a few. Using databases to store geospatial data is relatively easy, considering the aforementioned benefits.
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There are multiple types of databases; however, the most common type of database, and the type of database that this chapter will cover, is the relational database.
A relational database stores data in tables. A table is composed of rows and columns, where each row is a single data record and each column stores a field value associated with each record. A table can have any number of records; however, each field is uniquely named and stores a specific type of data.
A data type restricts the information that can be stored in a field, and it is very important that an...