删除SQL查询中的重复项

Question

W3Schools的SQL实践

SELECT C.country, 
       Round(Sum(P.price * OD.quantity), 2) AS Revenue 
FROM   [orders] AS O 
       INNER JOIN [orderdetails] AS OD 
               ON O.orderid = OD.orderid 
       INNER JOIN [products] AS P 
               ON OD.productid = P.productid 
       INNER JOIN [customers] AS C 
               ON O.customerid = C.customerid 
WHERE  C.country = (SELECT C.country 
                    FROM   [orders] AS O 
                           INNER JOIN [orderdetails] AS OD 
                                   ON O.orderid = OD.orderid 
                           INNER JOIN [products] AS P 
                                   ON OD.productid = P.productid 
                           INNER JOIN [customers] AS C 
                                   ON O.customerid = C.customerid 
                    GROUP  BY C.customerid 
                    ORDER  BY Round(Sum(P.price * OD.quantity), 2) DESC 
                    LIMIT  1)

我的联接从主查询重复到子查询。 无论如何，是否可以减少此查询中的代码复制？