SELECT s.sede, s.url, area_url, categorie.url AS cat_url 
FROM sedi AS s 
INNER JOIN prodotti AS p ON s.url=p.sede_url 
INNER JOIN categorie ON id_cat=cod 
INNER JOIN aree ON id_area=area_id 
INNER JOIN prodotti_immagini i ON ( codice_id = user AND p.id_art = i.id_art )
WHERE id_area= 
AND attivo = 'y' 
AND venduto ='false' 
AND dif='false' 
AND spedizione='y'
GROUP BY id_sede ORDER BY sede ASC