Tables in a database or geodatabase can contain some types of information that file-based tables do not support. For example, database or geodatabase tables can store BLOB or raster field types. In addition, databases and geodatabases provide capabilities to extend the functionality of tables, such as maintaining data integrity and managing transactions.
In the geodatabase, descriptive attributes are often held in the feature class table or within a related table to describe the individual features.
The process of defining tables builds on fundamental relational concepts, and a similar relational design process is employed for organizing tables within a database or geodatabase used with ArcGIS.
Here are the fundamental steps for table design:
- Identify the type of objects you want to describe in your table. For example:
- Owners for parcels
- The soil type and descriptive information about each soil polygon
- Properties and descriptions of buildings
- Demographic attributes of census tracts or blocks
- Simple descriptive attributes of places within your study area
- Identify the set of attribute fields you want to record about these objects.
- Define the types of fields and values you will use to store these properties. For example:
- A Name field might be used to record the name of the object in 25 characters or less.
- A Road Class field of two-digit integer values might be used to classify roads.
- Various numeric fields might be used to record measurements about the objects.
- A Date field might be used to specify the date of a parcel conveyance.
- Give each field a name and a data type. See Data types for more information.
- Organize these fields into one or more tables about the objects.
- Define the rules for values within each field. Use these to define geodatabase domains, which can be used to manage the integrity of field values in a geodatabase table column.
- In cases where more than one table is to be used, define the relationship properties between the tables.