Can't execute query

        SELECT r.id, r.id_kategorieref, r.datum, r.nazev, r.body, r.image1, r.popis1, r.image2, r.popis2, r.image3, r.popis3, r.image4, r.popis4, r.image5, r.popis5, r.image6, r.popis6, r.image7, r.popis7, r.image8, r.popis8, r.image9, r.popis9, r.image10, r.popis10, k.id, k.nazev as typn
        FROM reference r, kategorieref k
        WHERE  r.id_kategorieref = 
        AND k.id = 
        ORDER BY r.id_kategorieref, r.nazev
        

MySQL Error: You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'AND k.id = ORDER BY r.id_kategorieref, r.nazev' at li

This script cannot continue, terminating.