Relationship classes

In a geodatabase, a relationship between two tables is stored in a relationship class. Unlike ArcMap table joins and relates, which are saved only in a map document, relationships stored in a relationship class persist for the life of the relationship class.

Relationship classes are created in ArcCatalog or using a geoprocessing tool. A relationship class can be created inside a feature dataset or at the root level of the geodatabase; the tables participating in the relationship class must be in the same geodatabase. If you delete a feature class or nonspatial table that participates in a relationship class, then the relationship class is also deleted.

Once you have created a relationship class, you cannot modify its properties (see next point).

The ParcelOwners relationship class was created at the root level of the CityWater geodatabase and defines the relationship between the Parcels feature class and the Owners table.

Only two tables can be related in a single relationship class. To create a relationship between more than two tables, you can set up a stacked relationship, where table A is connected to table C through table B. To create a stacked relationship, first create a relationship class relating table A with table B, then create a second relationship class relating table B with table C.