Private void ConstraintsDemo ( DataSet myDataSet, string table1, 
      string table2, string column1, string column2 ) {
   ForeignKeyConstraint idKey = new ForeignKeyConstraint
      ( myDataSet.Tables [ Table1 ].Columns [ Column1 ],
      myDataSet.Tables [ Table2 ].Columns [ Column2 ] );
   // set null values when a value is deleted.
   idKey.DeleteRule = Rule.SetNull;
   idKey.UpdateRule = Rule.Cascade;
   // set AcceptRejectRule to cascade changes.
   idKey.AcceptRejectRule = AcceptRejectRule.Cascade;

   myDataSet.Tables [ Table1 ].Constraints.Add ( idKey );
   myDataSet.EnforceConstraints = true;
}

Private Sub ConstraintsDemo ( myDataSet As DataSet, table1 As String, _
      table2 As String, column1 As String, column2 As String )
   Dim idKey As New ForeignKeyConstraint _
      ( myDataSet.Tables ( table1 ).Columns ( column1 ), _
      myDataSet.Tables ( table2 ).Columns ( column2 ) )
   ' set null values when a value is deleted.
   idKey.DeleteRule = Rule.SetNull
   idKey.UpdateRule = Rule.Cascade
   ' set AcceptRejectRule to cascade changes.
   idKey.AcceptRejectRule = AcceptRejectRule.Cascade

   myDataSet.Tables ( table1 ).Constraints.Add ( idKey )
   myDataSet.EnforceConstraints = True
End Sub