private void GetParentCols ( ) {
   // get the data relation
   DataRelation dr = myDataSet.Relations [ "CustomerOrders" ]
   // get the parent columns.
   DataColumn [ ] parentCols = dr.ParentColumns;
   // print the ColumnName of each column.
   int i;
   for ( i = 0; i < parentCols.Length; i++ ) {
      Response.Write ( parentCols [ ].ColumnName );
   }
}

Private Sub GetParentCols ( )
   ' get the data relation
   Dim dr As DataRelation = myDataSet.Relations ( "CustomerOrders" )
   ' get the parent columns.
   Dim parentCols ( ) As DataColumn = dr.ParentColumns
   ' print the ColumnName of each column.
   Dim i As Integer
   For i = 0 to Ubound ( parentCols )
      Response.Write ( parentCols ( i ).ColumnName )
   Next i
End Sub