在delphi中我用DBGrid选择多条记录,如何一次把选择的多条记录删掉

procedure TForm1.btnDoSumClick(Sender: TObject);
var
  i: Integer;
begin
  if DBGrid1.SelectedRows.Count > 0 then
  begin
    with DBGrid1.DataSource.DataSet do
    begin
      for i := 0 to DBGrid1.SelectedRows.Count-1 do
      begin
        GotoBookmark(Pointer(DBGrid1.SelectedRows.Items[i]));
        self.ADOQuery1.Delete;//删除记录
      end;
    end;
  end
end;

我的这段程序是这样的.

procedure TForm1.Button1Click(Sender: TObject);
begin
  ShowMessage('删除前记录数:'+IntToStr(ADOQuery1.RecordCount));
  try
    DBGrid1.SelectedRows.Delete;
  except

  end;
  ADOQuery1.Close;
  ADOQuery1.Open;
  ShowMessage('删除后记录数:'+IntToStr(ADOQuery1.RecordCount));
end;