Relations belonging to the DataSet are stored as DataRelation objects in a DataRelationCollection object and are accessed through the Relations property of the DataSet . Each DataRelation object represents the relationship between a parent and child table in the DataSet . This section examines some methods and properties of the DataRelationCollection . Relations are added to the DataSet using the Add( ) method of the DataRelationCollection , as shown in the following example: ds.Relations.Add("MyDataRelation", parentTable.Columns["PrimaryKeyField"], childTable.Columns["ForeignKeyField"]); The Remove( ) method removes a relation matching the relation- name argument. The following example removes the relation added in the previous example: ds.Relations.Remove("MyDataRelation"); The Contains( ) method can determine if a specific relation exists as shown in the following example: Boolean exists = ds.Relations.Contains("MyRelation"); Relations and the DataRelationCollection are discussed in detail in Chapter 11. |