Benefits of relationship classes(ArcInfo and ArcEditor only)
Release 9.3 Last modified October 12, 2010	Print all topics in : "Relationship classes"

Note: This topic was updated for 9.3.1.

Geodatabase relationship classes are similar to relationships you can set up with a database management system. Relationship classes manage the associations between objects in one class (feature class or table) and objects in another. Objects at either end of the relationship can be features with geometry or records in a table.



Relationship classes support all cardinalities—one-to-one, one-to-many, and many-to-many—and may have attributes about the relationship itself.

Relationship classes also provide many advanced capabilities not found in ArcMap joins and relates.

• Relationship classes help enforce referential integrity.
  

A relationship class can be set up so when you modify an object, related objects update automatically. This can involve physically moving related features, deleting related objects, or updating an attribute. For example, you could set up a relationship such that whenever you move a utility pole, attached transformers and other equipment move with it.

By setting rules, a relationship class can restrict the type of relations that are valid. For example, a pole may support a maximum of three transformers. A steel pole may support class A transformers but not class B transformers.

Relationship classes actively maintain the referential integrity between related classes, even if one of them has not been added to the ArcMap session.


• Relationship classes facilitate editing, helping you lower maintenance costs.
  

By providing automatic updates to related objects, a relationship class can save you from performing additional edit operations.

Relationship classes help you access objects while you're editing. You can select an object, then use the Attributes dialog box or table to find all related objects. Once you have navigated to the related object, you can edit its attributes. Regardless of how deeply chained, all the related classes are available for editing.

Because relationship classes are stored in the geodatabase, they can be managed with versions. Versions allow multiple users to edit the features or records in a relationship at the same time.


• Relationship classes allow you to query related features and records. Similar to an ArcMap join, you can query, perform analysis, and generate reports with attributes from a related class.
  


• There are no limitations with respect to differing resolutions. Simple and composite relationship classescan be made up of feature classes of different resolutions.
  

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