procedure TForm1.Button1Click(Sender: TObject);
const
  DBPath: String = 'localhost/3302:d:\temp\Employee.fdb';
  ChrSet: String = 'UTF8';
  LibName: String = 'd:\Portable_program\Firebird_server\Firebird_3_0_2\fbclient.dll';
  UsrNm: String = 'sysdba';
  PW: String = 'cooladmin';
var
  Dbase: TIBDataBase;
  ReadTrans: TIBTransaction;
  Qry: TIBQuery;
  DS: TDataSource;
begin
  Dbase:= TIBDataBase.Create(Application);
  ReadTrans:= TIBTransaction.Create(Application);
  Qry:= TIBQuery.Create(Application);
  DS:= TDataSource.Create(Application);
  try
    with Dbase do
    begin
      DatabaseName:= DBPath;
      DefaultTransaction:= ReadTrans;
      LoginPrompt:= False;
      LibraryName:= LibName;
      Params.Add('lc_ctype=' + ChrSet);
      Params.Add('user_name=' + UsrNm);
      Params.Add('password=' + PW);
    end;

    with ReadTrans do
    begin
      Params.Add('read');
      Params.Add('read_committed');
      Params.Add('rec_version');
      Params.Add('nowait');
      DefaultDatabase:= Dbase;
    end;

    with Qry do
    begin
      Database:= Dbase;
      Transaction:= ReadTrans;
      AutoFetchAll:= True;
      SQL.Text:= 'SELECT COUNTRY, CURRENCY FROM COUNTRY';
    end;

    DS.DataSet:= Qry;
    DBGrid1.DataSource:= DS;

    try
      if not Dbase.Connected then Dbase.Connected:= True;
      try
        ReadTrans.Active:= True;
        try
          Qry.Active:= True;
        except
          on E:EIBError do //uses IB
          begin
            ShowMessage(E.Message);
            Exit;
          end;
        end;
      except
        on E:EIBError do
        begin
          ShowMessage(E.Message);
          Exit;
        end;
      end;
    except
      on E:EIBError do
      begin
        ShowMessage(E.Message);
        Exit;
      end;
    end;

    ShowMessage('Connected!');
  finally
    FreeAndNil(DS);
    FreeAndNil(Qry);
    FreeAndNil(ReadTrans);
    FreeAndNil(Dbase);
  end;
end;