procedure TForm1.BitBtn1Click(Sender: TObject);
var
  I:  Integer;
  Str: string;
begin
  Str := '';
  if DBGrid1.SelectedRows.Count > 0 then
  begin
    with DBGrid1.DataSource.DataSet do
      for I := 0 to DBGrid1.SelectedRows.Count-1 do
      begin
        GotoBookmark(pointer(DBGrid1.SelectedRows.Items[I]));
        if I > 0 then
          Str := Str ', ';
        Str:= Str #39 FieldByName('KeyField').AsString #39;
      end;
    with Query2 do//另一Query
    begin
      Close;
      SQL.Clear;
      SQL.Add('Select * From TableName Where KeyField in (' Str ')');
      Open;
    end;
  end;
end;