SELECT * FROM opony ORDER BY cena LIMIT 10;
SELECT producent, model, sezon, cena FROM opony WHERE nr_kat = 9;
SELECT id_zam, ilosc, model, cena FROM zamowienie JOIN opony USING(nr_kat) ORDER BY RAND() LIMIT 1;
UPDATE opony SET cena = cena * 0.75 WHERE sezon = 'letnia';