Deciding between relationship classes, relates, and joins

Available with Standard or Advanced license.

Note:

Although relationship classes can be both created and edited in ArcGIS Desktop Advanced and ArcGIS Desktop Standard, they are read-only in ArcGIS Desktop Basic. The feature classes participating in the relationship class will also be read-only in ArcGIS Desktop Basic.

Relationship classes help ensure referential integrity. For example, the deletion or modification of one feature could delete or alter a related feature. Furthermore, a relationship class is stored in the geodatabase, which makes it accessible to anyone who uses the geodatabase.

On-the-fly relationships, also called relates, are defined as a property of an ArcMap layer. Use them for improved editing performance.

Joins are best suited for labeling and symbology. You define joins through the relational database to make standard SQL queries cross the database as well as a variety of data sources.

Relationship classes, relates, and joins

	Relationship classes	On-the-fly relates	Joins
Typical uses	Ensuring data integrity	Editing with low overhead	Labeling, symbology
Scope	Geodatabase	Cross database or data source	Cross database or data source
Framework	Geodatabase data model	Defined in map layer	Relational database/SQL
User interface for editing	ArcMap	VBA application in ArcMap	SQL queries
User interface for navigating	ArcMap	ArcMap	SQL queries
Composite objects	Yes	No	No
Referential integrity	Yes	No	No
Messaging	Yes	No	No
Attributes	Yes	No	No
Relationship rules	Yes	No	No
Cardinality	One-to-one, one-to-many, many-to-many	One-to-one, one-to-many, many-to-many	One-to-one, many-to-one
Pros	Manages referential integrity and messaging behavior via ArcMap attributes inspector	No editing overhead, can cross workspace and data source type	No editing overhead; can cross workspace and data source type; can be used for SQL queries, labeling, and symbology
Cons	Incurs editing overhead; must be defined only between tables in same geodatabase within the same user schema; still requires joins for SQL query, labeling, and symbology	No referential integrity; no messaging; still requires joins for SQL query, labeling, and symbology	No referential integrity, no messaging, no support for many-to-many relationships; one-to-many relationships involving feature classes not supported