Spatial database concepts
As mentioned in the previous chapter, spatial databases are databases which can store and query spatial data. Each record in a spatially-enabled database table has one or more geometry fields which position that record somewhere on the Earth's surface. How the geometry field(s) are used will depend on what type of information you are storing in the database table. For example:
A record representing a delivery vehicle might include a Point geometry reflecting the vehicle's current location.
A record representing a road might include a LineString geometry representing the shape of the road.
A record representing a forest fire might include a Polygon geometry representing the area affected by the fire.
Note
Some spatial databases allow you to have multiple geometry fields, while others are limited to just one per record.
By itself, a geometry field is simply a database blob which can hold the encoded geometry data. The data is usually stored in Well-Known Binary (WKB) format...
