Question

我有订单中的订单项，其中一些是买一送一优惠。其业务逻辑是：

一对中最便宜的物品是免费的
选择了最适合客户的交易
在商品中使用商品后，无法再次使用

以下是一些订单项（OrderItemID）的示例，这些订单项已加入其所有优惠中。

╔═════════════╦═════════╦═══════╗
║ OrderItemID ║ OfferID ║ Value ║
╠═════════════╬═════════╬═══════╣
║ 1           ║ 1       ║ 22.50 ║
║ 2           ║ 1       ║ 25.00 ║
║ 3           ║ 2       ║ 14.99 ║
║ 4           ║ 1       ║ 5.00  ║
║ 5           ║ 1       ║ 7.00  ║
║ 5           ║ 2       ║ 7.00  ║
║ 5           ║ 3       ║ 7.00  ║
║ 6           ║ 3       ║ 7.50  ║
╚═════════════╩═════════╩═══════╝

从这里我可以使用上面的规则得出完整的有效组合，按照保存（即第二项的价格）排序：

╔═════════════════╦═════════════════╦═════════╦═══════╦════════╗
║ PaidOrderItemID ║ FreeOrderItemID ║ OfferID ║ Price ║ Saving ║
╠═════════════════╬═════════════════╬═════════╬═══════╬════════╣
║ 2               ║ 1               ║ 1       ║ 25.00 ║ 22.50  ║
║ 1               ║ 5               ║ 1       ║ 22.50 ║ 7.00   ║
║ 2               ║ 5               ║ 1       ║ 25.00 ║ 7.00   ║
║ 3               ║ 5               ║ 2       ║ 14.99 ║ 7.00   ║
║ 6               ║ 5               ║ 3       ║ 7.50  ║ 7.00   ║
║ 1               ║ 4               ║ 1       ║ 22.50 ║ 5.00   ║
║ 2               ║ 4               ║ 1       ║ 25.00 ║ 5.00   ║
║ 5               ║ 4               ║ 1       ║ 7.00  ║ 5.00   ║
╚═════════════════╩═════════════════╩═════════╩═══════╩════════╝

我现在想要提取组合，而不会在订单商品中重叠。下表显示了我需要的内容

╔═════════════════╦═════════════════╦═════════╦═══════╦════════╗
║ PaidOrderItemID ║ FreeOrderItemID ║ OfferID ║ Price ║ Saving ║
╠═════════════════╬═════════════════╬═════════╬═══════╬════════╣
║ 2               ║ 1               ║ 1       ║ 25.00 ║ 22.50  ║
║ 3               ║ 5               ║ 2       ║ 14.99 ║ 7.00   ║
╚═════════════════╩═════════════════╩═════════╩═══════╩════════╝

第一行是保存最高的一行。下一行是PaidOrderItemID和FreeOrderItemID与第一行中使用的ItemID不同的第一行。

我有这个工作，使用游标将顶行提取到临时表，然后使用相同的OrderItemID删除商品，重复直到没有商品剩余。

我想知道是否有办法可以使用基于集合的方法完成？我尝试过使用递归CTE方法而没有运气。代码需要在SQL Server 2008 R2上运行。

示例的代码如下：

DECLARE @orderItemOffers TABLE (OrderItemID INT, OfferID INT, Value MONEY)
INSERT INTO @orderItemOffers
        (OrderItemID, OfferID, Value)
VALUES  (1, 1, 22.50),
        (2, 1, 25.00),
        (3, 2, 14.99),
        (4, 1, 5.00),
        (5, 1, 7.00),
        (5, 2, 7.00),
        (5, 3, 7.00),
        (6, 3, 7.50)

SELECT * FROM @orderItemOffers

DECLARE @offerCombos TABLE (
    PaidOrderItemID INT,
    FreeOrderItemID INT,
    OfferID INT,
    Price MONEY,
    Saving MONEY
)
INSERT INTO @offerCombos (
    PaidOrderItemID,
    FreeOrderItemID,
    OfferID,
    Price,
    Saving
)
SELECT PaidItem.OrderItemID,
       FreeItem.OrderItemID,
       FreeItem.OfferID,
       PaidItem.Value,
       FreeItem.Value
FROM @orderItemOffers PaidItem
INNER JOIN @orderItemOffers FreeItem
    ON FreeItem.OrderItemID <> PaidItem.OrderItemID
       AND FreeItem.OfferID = PaidItem.OfferID
       AND (FreeItem.Value < PaidItem.Value 
            OR (FreeItem.Value = PaidItem.Value
                AND FreeItem.OrderItemID > PaidItem.OrderItemID
               )
           )
ORDER BY FreeItem.Value DESC

SELECT * FROM @offerCombos

DECLARE @takenOffers TABLE (
    PaidOrderItemID INT,
    FreeOrderItemID INT,
    OfferID INT,
    Price MONEY,
    Saving MONEY
)
DECLARE offerCursor CURSOR FAST_FORWARD FOR SELECT * FROM @offerCombos
OPEN offerCursor

DECLARE @PaidOrderItemID INT, @FreeOrderItemID INT,
        @OfferID INT, @Price MONEY, @Saving MONEY
FETCH NEXT FROM offerCursor
INTO @PaidOrderItemID, @FreeOrderItemID, @OfferID, @Price, @Saving

WHILE @@FETCH_STATUS = 0
BEGIN
    INSERT INTO @takenOffers
           (PaidOrderItemID, FreeOrderItemID, OfferID, Price, Saving)
    VALUES (@PaidOrderItemID, @FreeOrderItemID, @OfferID, @Price, @Saving)

    DELETE FROM @offerCombos
    WHERE PaidOrderItemID IN (@PaidOrderItemID, @FreeOrderItemID)
       OR FreeOrderItemID IN (@PaidOrderItemID, @FreeOrderItemID)

    FETCH NEXT FROM offerCursor
    INTO @PaidOrderItemID, @FreeOrderItemID, @OfferID, @Price, @Saving
END 

CLOSE offerCursor
DEALLOCATE offerCursor

SELECT * FROM @takenOffers

Answer 1

你可以从这样的事情开始

WITH Offer AS (
SELECT *, rn=ROW_NUMBER() OVER (PARTITION BY OfferID ORDER BY Value DESC)
FROM @orderItemOffers
)
SELECT 
    o1.OrderItemID AS PaidOrderItemID 
    ,o2.OrderItemID AS FreeOrderItemID
    ,o1.OfferID
    ,o1.Value AS Price
    , o2.Value as Saving
FROM Offer o1
LEFT JOIN Offer o2 
    ON o1.OfferID = o2.OfferID
    AND o1.rn = o2.rn -1
WHERE o1.rn % 2 = 1
ORDER BY OfferID,PaidOrderItemID

的 sql fiddle demo 的

Answer 2

这个怎么样？

SELECT *, (ROW_NUMBER() OVER(PARTITION BY OfferID ORDER BY Value DESC, OrderItemID) - 1) % 2 IsFree
FROM @orderItemOffers

在要约中，按值按降序对项目进行编号;所有其他项目都是免费的，因为它是下一个最高价值。

行对没有重叠

2 个答案: