procedure TForm1.DBEdit1Exit(Sender: TObject);
begin
  if Table1.state = dsInsert then
  begin
    if (DBEdit1.Text <> '') and (DBEdit2.Text <> '') then
    begin
      Query1.Close; //這裡你要用另外一個Query來做
      Query1.SQL.Clear;
      Query1.SQL.ADD(' SELECT COUNT(*) as xcount FROM Property WHERE Classification='   #39   DBEdit1.Text   #39   ' AND Numbers='   #39   DBEdit2.Text   #39);
      Query1.Open;
      if Query1.FieldByName('xcount').Value < 1 then
      begin
        Query1.Close;
      end
      else
      begin
        SHOWMESSAGE('資料重覆!!!'); //Message在這裡你可以自己改成你要的..
        DBEdit1.setfocus;
        Query1.Close;
        exit;
      end;
    end;
  end;
end;