SELECT Item.*, MIN(Offer.price) minOfferPrice
FROM Item
LEFT JOIN Offer ON Item.id = Offer.item_id
GROUP BY Item.id
HAVING (Item.minPrice != minOfferPrice);
SELECT Item.*
FROM Item i
JOIN (
SELECT
o.item_id
, MIN(o.price) AS minPrice
FROM Offer o
GROUP BY o.item_id
) sel ON sel.item_id = i.id
WHERE i.minPrice != sel.minPrice