Delphi7 - Autentifikasi

procedure TfAuth.Button1Click(Sender: TObject);
begin
  if(Edit1.Text='') or (Edit2.Text='')then
  begin
    ShowMessage('Username dan Password Harus diisi..!!!');
  end
    else
  begin
    with DM.ADOQuery1 do
    begin
      Active:=False;
      Close;
      SQL.Clear;
      SQL.Text:='SELECT username FROM users WHERE username='+
                QuotedStr(Edit1.Text)+
                'AND password='+ QuotedStr(Edit2.Text);
      Active:=True;
    end;

    if DM.ADOQuery1.IsEmpty then
    begin
      ShowMessage('Username dan Password Salah..!!!');
      Edit1.Text:='';
      Edit2.Text:='';
    end
      else
      begin
        ShowMessage('Selamat datang..!!!');
        fAuth.Hide;
        fMain.Show;
      end;

  end;
end;