SELECT k.adoszam, MAX(k.nev) as nev, MAX(nav.utolso_mukodes) as OnlineSzamla
   FROM kr_2007_kliens_info k
   LEFT JOIN kr_2007_nav_kliens_info nav ON nav.adoszam = k.adoszam
  WHERE k.utolso_bejelentkezes_datum = current_date
    AND k.adoszam <> ''
  GROUP BY k.adoszam