Question

我正在使用MS SQL。我有两张桌子：

1）“OrderProducts” - 此表存储订单的所有产品。还有另一个Orders主表，我们可以从这张图中省略。订单主表存储订单的主数据，而OrderProducts表存储详细信息。

2）“TransactionFeeProducts” - 此表存储我想要为订单收取的所有产品的交易费用。它有一个BatchID，其中多个产品可以具有相同的BatchID。

基本上，OrderDate所有订购的产品介于TransactionFeeProducts.FromDate和TransactionFeeProducts.ToDate之间，将收取TransactionFeeProducts.TransactionFee

OrderProducts

的ProductID
数量
订购日期

TransactionFeeProducts

BatchID
的ProductID
FROM日期
TODATE
TransactionFee

SQL：

SELECT SUM(Quantity) as Orders, 
TransactionFeeProducts.ProductID, FromDate, ToDate 
FROM TransactionFeeProducts 
LEFT JOIN OrderProducts ON TransactionFeeProducts.ProductID = OrderProducts.ProductID
WHERE
OrderDate >= TransactionFeeProducts.FromDate AND 
OrderDate <= TransactionFeeProducts.ToDate AND 
TransactionFeeProducts.BatchID = 3
GROUP BY TransactionFeeProducts.ProductID, FromDate, ToDate 
ORDER BY SUM(Quantity) DESC

我希望SQL在TransactionFeeProducts中返回BatchID = 3的所有记录。 SUM（Quantity）应该只给我在TransactionFeeProducts.FromDate和TransactionFeeProducts.ToDate之间的OrderDate的总和

如果SUM（Quantity）为0，则该字段应为NULL或0。

我现在的问题是，如果SUM（Quantity）为0，则SQL不会返回任何记录。

请帮忙。非常感谢你。

Answer 1

将JOIN条件更改为

SELECT  SUM(Quantity) as Orders,  
        TransactionFeeProducts.ProductID, 
        FromDate, 
        ToDate  
FROM    TransactionFeeProducts LEFT JOIN 
        OrderProducts   ON  TransactionFeeProducts.ProductID = OrderProducts.ProductID 
                        AND OrderDate >= TransactionFeeProducts.FromDate 
                        AND OrderDate <= TransactionFeeProducts.ToDate 
WHERE   TransactionFeeProducts.BatchID = 3 
GROUP BY    TransactionFeeProducts.ProductID, 
            FromDate, 
            ToDate  
ORDER BY    SUM(Quantity) DESC

不同之处在于，如果将过滤条件放在WHERE子句中，它将影响查询过滤，就像使用INNER JOIN一样，说明您只包含来自TransactionFeeProducts其中OrderDate >= TransactionFeeProducts.FromDate and OrderDate <= TransactionFeeProducts.ToDate

看一下以下示例

DECLARE @TABLE1 TABLE(
        ID INT,
        FromDate DATETIME,
        ToDate DATETIME
)

INSERT INTO @TABLE1 SELECT 1, '01 Jan 2012','31 Jan 2012'

DECLARE @TABLE2 TABLE(
        ID INT,
        DateValue DATETIME
)

INSERT INTO @TABLE2 SELECT 1, '01 Feb 2012'

SELECT  *
FROM    @TABLE1 t1 LEFT JOIN
        @TABLE2 t2  ON  t1.ID = t2.ID
                    AND t2.DateValue BETWEEN t1.FromDate AND t1.ToDate

SELECT  *
FROM    @TABLE1 t1 LEFT JOIN
        @TABLE2 t2 ON   t1.ID = t2.ID
WHERE   t2.DateValue BETWEEN t1.FromDate AND t1.ToDate

选择1说：

返回T1中的所有行，仅返回来自t1.ID = t2.ID AND t2.DateValue BETWEEN t1.FromDate AND t1.ToDate

的T2的所有行

另一方面选择2说：

返回T1中的所有行，只返回来自T2 t1.ID = t2.ID的所有行，然后返回t2.DateValue BETWEEN t1.FromDate AND t1.ToDate

之前的行

SQL SERVER – Introduction to JOINs – Basic of JOINs总是很方便。

Answer 2

我更喜欢astander的方法（在JOIN中过滤），但有时候有用的替代方法是在加入字段上添加一个OR IS NULL，例如。

WHERE
 TransactionFeeProducts.BatchID = 3
 AND
(OrderProducts.ProductID IS NULL
 OR 
(
   OrderDate >= TransactionFeeProducts.FromDate AND 
   OrderDate <= TransactionFeeProducts.ToDate 

))

LEFT JOIN条件

OrderProducts

TransactionFeeProducts

2 个答案: