ArcGIS Pro 2.7 API Reference Guide
Relationship Class
Members 

ArcGIS.Core.Data Namespace : Relationship Class
Represents a pair of related rows (or features) from a geodatabase.
Object Model
Relationship ClassRow ClassRow Class
Syntax
public class Relationship : ArcGIS.Core.CoreObjectsBase, System.IDisposable  
Public Class Relationship 
   Inherits ArcGIS.Core.CoreObjectsBase
   Implements System.IDisposable 
Remarks
A Relationship represents a relationship between rows and/or features where the tables or feature classes must participate in a RelationshipClass. In this type of relationship, there is no intermediate table to store information about the related rows/features. Relationships are created using RelationshipClass.CreateRelationship and are returned using RelationshipClass.GetRowsRelatedToOriginRows or RelationshipClass.GetRowsRelatedToDestinationRows.
Inheritance Hierarchy

System.Object
   ArcGIS.Core.CoreObjectsBase
      ArcGIS.Core.Data.Relationship
         ArcGIS.Core.Data.AttributedRelationship

Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

Relationship Members
ArcGIS.Core.Data Namespace
AttributedRelationship Class