Introduction
Real-world objects can be represented in Geographic Information Systems (GIS) using geographic data. In the context of the Esri ArcGIS technology, a database that stores geographic data is a geodatabase. The geodatabase is a native ArcGIS format that allows you to store, edit, and manage spatial data and non-spatial data. Before you start adding data to a geodatabase, it is important to think about how your data will be organized in the geodatabase. Another important step is to create an empty but structured schema of your geodatabase (data model). Paul A. Longley (Geographical Information Systems and Science, 2nd Edition, 2005, John Wiley & Sons, Inc , p.178) has mentioned three steps in creating a geospatial data model:
- Conceptual schema
- Logical schema
- Physical schema (geodatabase schema)
In this chapter, you will skip steps 1 and 2, and you will manually create the physical schema or the geodatabase structure.
Note
There are three types of geodatabases: personal geodatabase, file geodatabase, and multiuser geodatabase. For more information about geodatabases, please refer to http://www.esri.com/software/arcgis/geodatabase.
For comprehensive definitions of specific elements and terms such as geodatabase, file geodatabase, feature dataset, spatial domain, resolution, tolerance, subtype, domain, feature class, relationship, or referential integrity, please refer to the ESRI GIS Dictionary online at http://support.esri.com/en/knowledgebase/GISDictionary.
In this chapter, you will work with the most common geodatabase elements, such as feature dataset, feature class, table, and relationship class. You will test the main advantages of using a geodatabase by performing the following actions:
- Define the common spatial reference using feature datasets
- Organize the features with the same geometry and spatial reference in feature classes
- Define attribute constraints to eliminate edit errors using subtypes, domains, and default values
- Define spatial and non-spatial relationships using relationship classes
- Add supplementary spatial and attribute behaviors by defining relationship rules for relationship classes
