MySql:返回连接表中的最大值

Question

我这里加入了 3 张 table 。其中包括客户、订单和客户订购的商品。它们被命名为:CustomersTbl、OrdersTbl、OrderedItemTbl。

我正在排列所有订单及其总价，并显示下订单的客户的姓名。

select * from productstbl;
select * from ordereditemtbl;
select * from orderstbl;

select 
    ordereditemtbl.ItemID,
    customerstbl.CustomerID,
    customerstbl.FirstName,
    orderstbl.OrderID,
    orderstbl.OrderDate,
    sum(ordereditemtbl.amount * productstbl.Price) as totalPrice
from
    ordereditemtbl
        inner join
    ProductsTbl ON ordereditemtbl.productID = productstbl.productID
        inner join
    orderstbl ON ordereditemtbl.orderID = ordereditemtbl.orderID
        inner join
    customerstbl ON customerstbl.customerID = orderstbl.customerID#'2'
group by ordereditemTbl.OrderID
order by totalPrice desc;

现在我想单独显示 TotalPrice 最高的订单。我怎样才能得到它的最大值？有没有办法可以使用 MAX() 函数？

Answer 1

让我们看看。看看这是否有效:

SELECT * FROM 
(
select 
    ordereditemtbl.ItemID,
    customerstbl.CustomerID,
    customerstbl.FirstName,
    orderstbl.OrderID,
    orderstbl.OrderDate,
    sum(ordereditemtbl.amount * productstbl.Price) as totalPrice,
    @rownum AS row_number
from
    ordereditemtbl
        inner join
    ProductsTbl ON ordereditemtbl.productID = productstbl.productID
        inner join
    orderstbl ON ordereditemtbl.orderID = ordereditemtbl.orderID
        inner join
    customerstbl ON customerstbl.customerID = orderstbl.customerID#'2'
        inner join
    (SELECT @rownum := 0) dummy
group by ordereditemTbl.OrderID
ORDER BY totalPrice desc;
)
WHERE row_number=0

这会分配行号并选择顶行。

干杯， 公羊