SELECT o.demot_id, o.demot_wszystkie_oceny, d.demot_id FROM `demoty` d LEFT JOIN `oceny` ON o.demot_id = d.demot_id ORDER BY o.demot_wszystkie_oceny DESC;
SELECT id_news, ocena, ilosc_ocen FROM news n LEFT JOIN (SELECT id_news, Count(*) ilosc_ocen, Sum(ocena) ocena FROM oceny GROUP BY id_news) x ON x.id_news=n.id_news ORDER BY ocena DESC