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SQLServer2008的實(shí)用小道具 merger使用介紹

更新時間：2010年09月12日 21:42:40 作者：

根據(jù)在另一個表中找到的差異在一個表中插入、更新或刪除行，可以對兩個表進(jìn)行同步。

A. 使用 MERGE 在單個語句中對表執(zhí)行 UPDATE 和 DELETE 操作
　　下面的示例使用 MERGE 根據(jù) SalesOrderDetail 表中已處理的訂單，每天更新 AdventureWorks 示例數(shù)據(jù)庫中的 ProductInventory 表。通過減去每天對 SalesOrderDetail 表中的每種產(chǎn)品所下的訂單數(shù)，更新 ProductInventory 表的 Quantity 列。如果某種產(chǎn)品的訂單數(shù)導(dǎo)致該產(chǎn)品的庫存量下降到 0 或更少，則會從 ProductInventory 表中刪除該產(chǎn)品對應(yīng)的行。
　　B. 借助派生的源表，使用 MERGE 對目標(biāo)表執(zhí)行 UPDATE 和 INSERT 操作
　　下面的示例使用 MERGE 以更新或插入行的方式來修改 SalesReason 表。當(dāng)源表中的 NewName 值與目標(biāo)表 (SalesReason) 的 Name 列中的值匹配時，就會更新此目標(biāo)表中的 ReasonType 列。當(dāng) NewName 的值不匹配時，就會將源行插入到目標(biāo)表中。此源表是一個派生表，它使用 Transact-SQL 行構(gòu)造函數(shù)功能指定源表的多個行。有關(guān)在派生表中使用行構(gòu)造函數(shù)的詳細(xì)信息，請參閱 FROM (Transact-SQL)。

　　C. 將 MERGE 語句的執(zhí)行結(jié)果插入到另一個表中
　　下例捕獲從 MERGE 語句的 OUTPUT 子句返回的數(shù)據(jù)，并將該數(shù)據(jù)插入另一個表。MERGE 語句根據(jù)在 SalesOrderDetail 表中處理的訂單，更新 ProductInventory 表的 Quantity 列。本示例捕獲已更新的行，并將這些行插入用于跟蹤庫存變化的另一個表中

復(fù)制代碼代碼如下:

 
USE AdventureWorks; 
GO 
IF OBJECT_ID (N'Production.usp_UpdateInventory', N'P') 
IS NOT NULL DROP PROCEDURE Production.usp_UpdateInventory; 
GO 
CREATE PROCEDURE Production.usp_UpdateInventory 
@OrderDate datetime 
AS 
MERGE Production.ProductInventory AS target 
USING (SELECT ProductID, SUM(OrderQty) FROM Sales.SalesOrderDetail AS sod 
JOIN Sales.SalesOrderHeader AS soh 
ON sod.SalesOrderID = soh.SalesOrderID 
AND soh.OrderDate = @OrderDate 
GROUP BY ProductID) AS source (ProductID, OrderQty) 
ON (target.ProductID = source.ProductID) 
WHEN MATCHED AND target.Quantity - source.OrderQty <= 0 
THEN DELETE 
WHEN MATCHED 
THEN UPDATE SET target.Quantity = target.Quantity - source.OrderQty, 
target.ModifiedDate = GETDATE() 
OUTPUT $action, Inserted.ProductID, Inserted.Quantity, Inserted.ModifiedDate, Deleted.ProductID, 
Deleted.Quantity, Deleted.ModifiedDate; 
GO 
EXECUTE Production.usp_UpdateInventory '20030501' 

復(fù)制代碼代碼如下:

 
USE AdventureWorks; 
GO 
MERGE INTO Sales.SalesReason AS Target 
USING (VALUES ('Recommendation','Other'), ('Review', 'Marketing'), ('Internet', 'Promotion')) 
AS Source (NewName, NewReasonType) 
ON Target.Name = Source.NewName 
WHEN MATCHED THEN 
UPDATE SET ReasonType = Source.NewReasonType 
WHEN NOT MATCHED BY TARGET THEN 
INSERT (Name, ReasonType) VALUES (NewName, NewReasonType) 
OUTPUT $action, inserted.*, deleted.*; 

復(fù)制代碼代碼如下:

 
USE AdventureWorks; 
GO 
MERGE INTO Sales.SalesReason AS Target 
USING (VALUES ('Recommendation','Other'), ('Review', 'Marketing'), ('Internet', 'Promotion')) 
AS Source (NewName, NewReasonType) 
ON Target.Name = Source.NewName 
WHEN MATCHED THEN 
UPDATE SET ReasonType = Source.NewReasonType 
WHEN NOT MATCHED BY TARGET THEN 
INSERT (Name, ReasonType) VALUES (NewName, NewReasonType) 
OUTPUT $action, inserted.*, deleted.*; 

復(fù)制代碼代碼如下:

 
USE AdventureWorks; 
GO 
CREATE TABLE Production.UpdatedInventory 
(ProductID INT NOT NULL, LocationID int, NewQty int, PreviousQty int, 
CONSTRAINT PK_Inventory PRIMARY KEY CLUSTERED (ProductID, LocationID)); 
GO 
INSERT INTO Production.UpdatedInventory 
SELECT ProductID, LocationID, NewQty, PreviousQty 
FROM 
( MERGE Production.ProductInventory AS pi 
USING (SELECT ProductID, SUM(OrderQty) 
FROM Sales.SalesOrderDetail AS sod 
JOIN Sales.SalesOrderHeader AS soh 
ON sod.SalesOrderID = soh.SalesOrderID 
AND soh.OrderDate BETWEEN '20030701' AND '20030731' 
GROUP BY ProductID) AS src (ProductID, OrderQty) 
ON pi.ProductID = src.ProductID 
WHEN MATCHED AND pi.Quantity - src.OrderQty >= 0 
THEN UPDATE SET pi.Quantity = pi.Quantity - src.OrderQty 
WHEN MATCHED AND pi.Quantity - src.OrderQty <= 0 
THEN DELETE 
OUTPUT $action, Inserted.ProductID, Inserted.LocationID, Inserted.Quantity AS NewQty, Deleted.Quantity AS PreviousQty) 
AS Changes (Action, ProductID, LocationID, NewQty, PreviousQty) WHERE Action = 'UPDATE'; 
GO 