通过货币换算获取每种产品类型的最低价格

SELECt a.id, a.price*ISNULL(s.to_aud,1) as minprice
FROM
(
SELECt type_id, min((price+shipping)) as minprice
FROM products
GROUP BY type_id
) AS b INNER JOIN products as a on a.type_id = b.type_id and (a.price+a.shipping) = b.minprice
Inner join sellers s on s.id = a.seller_id
ORDER BY price