SELECT `goods`.`name`, MIN(`prices`.`price`)
FROM `goods`, `prices`
WHERE `goods`.`id` = `prices`.`good_id`                                            
GROUP BY `goods`.`id`

SELECT `goods`.`name`, MIN(`prices`.`price`), `stores`.`store_name`
FROM `goods`, `prices`, `stores`
WHERE `goods`.`id` = `prices`.`good_id`                                            
GROUP BY `goods`.`id`, `stores`.`id`

SELECT name, price, store_name
FROM goods, prices, stores
WHERE goods.id = prices.good_id
AND stores.id = prices.store_id
AND price
IN (
SELECT MIN(  `price` ) 
FROM goods, prices
WHERE goods.id = good_id
GROUP BY goods.id
)