Question

这是我的SQL查询，它连接两个表：

SELECT `o`.`orderID`,
       SUM(i.partialAmount) AS `amount`
FROM   `OrderTable` AS `o`
       INNER JOIN `Item` AS `i`
         ON i.orderID = o.orderID
GROUP  BY `o`.`orderID`

项目通过1对多关系连接到订单。每个项目都有一个partialAmount列，我将这些部分金额相加，以获得每个订单的总金额。

我想获得所有订单的总金额，怎么做？

所以我想要像：SUM（金额）AS totalAmount，但这不起作用：

SELECT `o`.`orderID`,
       SUM(i.partialAmount) AS `amount`,
       SUM(amount) AS `totalAmount`
FROM   `OrderTable` AS `o`
       INNER JOIN `Item` AS `i`
         ON i.orderID = o.orderID
GROUP  BY `o`.`orderID`

我不想使用WITH ROLLUP - 因为我不想要额外的行。

预期产出：

-----------------------------------------------------------------------
|   orderID       |        amount      |          totalAmount         |
-----------------------------------------------------------------------
|   1             |          2         |                5             |
-----------------------------------------------------------------------
|   2             |          3         |                5             |
-----------------------------------------------------------------------

Answer 1

如果您想要的只是一个总行，您可以执行类似此代码的操作。还有其他方法，具体取决于您是否需要过滤所选订单

SELECT `o`.`orderID`,
       SUM(i.partialAmount) AS `amount`
FROM   `OrderTable` AS `o`
       INNER JOIN `Item` AS `i`
         ON i.orderID = o.orderID
GROUP  BY `o`.`orderID` 
UNION
SELECT 999999,sum(i.partialAmount) as 'Amount'
FROM Item i

Answer 2

这会影响性能（并假设Item的每一行都有订单）：

SELECT `o`.`orderID`,
       SUM(i.partialAmount) AS `amount`,
       (SELECT SUM(partialAmount) FROM `Item`) TotalAmount
FROM   `OrderTable` AS `o`
       INNER JOIN `Item` AS `i`
         ON i.orderID = o.orderID
GROUP  BY `o`.`orderID`

Answer 3

我强烈建议在应用程序中执行此类操作而不是SQL，因为它是工作的重现，但它可以实现如下：

SELECT  OrderTable.OrderID, 
        SUM(PartialAmount) AS Amount,
        TotalAmount
FROM    OrderTable, 
        Item, 
        (SELECT SUM(PartialAmount) AS TotalAmount FROM Item) AS total
WHERE   Item.OrderID = Ordertable.OrderID
GROUP BY OrderTable.OrderID, TotalAmount

我无法检查执行计划，将其与Lamak在另一个答案中发布的Subselect选项进行比较，但SQL Server肯定会优化交叉应用，而不是subselect。

Answer 4

如果你想要每一行的总值，你可以使用sum（）而不是函数，这将给你两个总数 http://msdn.microsoft.com/en-us/library/ms189461.aspx

用于运行总计

sum(amount) over ()

部分总计

sum(amount) over (partition by o.orderid)

看起来像这样

SELECT distinct `o`.`orderID`,
       SUM(i.partialAmount) over (partition by orderid) AS `amount`,
       SUM(i.partialAmount) over () AS `totalAmount`
FROM   `OrderTable` AS `o`
       INNER JOIN `Item` AS `i`
        ON i.orderID = o.orderID

如何在INNER JOIN中对SUM的结果使用聚合SUM函数？

4 个答案: