You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'ORDER BY kategorie.poradi, stranky.poradi' at line 9
SELECT *, stranky.poradi as stranka_poradi FROM stranky LEFT JOIN kategorie ON kategorie.row_id = stranky.id_kategorie WHERE stranky.zverejnit='yes' AND kategorie.zverejnit='yes' and zverejnit_log_off='yes' AND nazev_stranky not like '' AND kategorie.nazev_kategorie not like '' AND (jen_superuser='no' or jen_superuser!='yes') AND id_kategorie= ORDER BY kategorie.poradi, stranky.poradi