如何使用TREEVIEW实现？ (50分)

type
  TAreaID = record
    ID: String[20];
    Len: Integer;
  end;
  PAreaID = ^TAreaID;

    with TQuery.Create(Self) do
    begin
        DatabaseName := 'BDETable';
        SQL.Add('select * from Area');
        SQL.Add('where LEN(AreaID) = :AreaLen');
        SQL.Add('order by AreaID');
        ParamByName('AreaLen').AsInteger := 2;
        Open();
        while not(Eof) do
        begin
            tmpNode := ZoneTree.Items.Add(nil, FieldByName('Area').AsString);
            new(AreaData);
            AreaData.ID := FieldByName('AreaID').AsString;
            AreaData.Len := 2;
            tmpNode.Data := AreaData;
            Next();
        end;
        Close();
        for i := 2 to 5 do
        begin
            ParamByName('AreaLen').AsInteger := i * 2;
            Open();
            while not(Eof) do
            begin
                tmpNode := nil;
                for j := ZoneTree.Items.Count - 1 downto 0 do
                begin
                    AreaData := ZoneTree.Items[j].Data;
                    if Copy(FieldByName('AreaID').AsString, 1, AreaData.Len) = AreaData.ID then
                    begin
                        tmpNode := ZoneTree.Items[j];
                        Break;
                    end;
                end;
                tmpNode := ZoneTree.Items.AddChild(tmpNode, FieldByName('Area').AsString);
                new(AreaData);
                AreaData.ID := FieldByName('AreaID').AsString;
                AreaData.Len := i * 2;
                tmpNode.Data := AreaData;
                Next();
            end;
            Close();
        end;
        Free();
    end;