我有订单中的订单项,其中一些是买一送一的优惠。其业务逻辑是:
- 一对中最便宜的商品是免费的
- 选择最适合客户的交易
- 商品在优惠中使用后将无法再次使用
以下是一些OrderItemID
已加入其所有报价的行项目 ( ) 的示例。
╔═════════════╦═════════╦═══════╗
║ 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 ║
╚═════════════╩═════════╩═══════╝
由此我可以使用上面的规则推导出完整的有效组合,按节省排序(即第二个项目的价格):
╔═════════════════╦═════════════════╦═════════╦═══════╦════════╗
║ 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 ║
╚═════════════════╩═════════════════╩═════════╩═══════╩════════╝
我现在想提取组合,而不会在订单项中重叠。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 ║
╚═════════════════╩═════════════════╩═════════╩═══════╩════════╝
第一行是储蓄最高的行。下一行是与第一行中PaidOrderItemID
使用FreeOrderItemID
的 s 不同ItemID
的第一行。
我使用游标将顶行提取到临时表中,然后使用相同OrderItemID
的 s 删除报价,重复直到没有报价。
我想知道是否有一种方法可以使用基于集合的方法来完成?我尝试过使用递归 CTE 方法,但没有成功。代码需要在 SQL Server 2008 R2 上运行。
该示例的代码如下:
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