此文章主要讲述的是SQL Server 2008 Merge语句之功能，OUTPUT，SQL Server 2005的Output功能能把Insert，Update以及Delete的内容全部都返回，2008数据库中的Output同样具有此功能，下面介绍一下把Output同2008的新T-SQL语句Merge组合使用的方法：
SQL Server 2005中的Output功能可以把Insert，Update和Delete的内容都返回，2008中的Output同样具有此功能，下面介绍一下把Output同2008的新T-SQL语句Merge组合使用的方法：
新建下面表：
view plaincopy to clipboardprint CREATE TABLE Book( ISBN varchar(20) PRIMARY KEY, Price decimal, Shelf int) CREATE TABLE WeeklyChange( ISBN varchar(20) PRIMARY KEY, Price decimal, Shelf int) CREATE TABLE BookHistory( Action nvarchar(10), NewISBN varchar(20), NewPrice decimal, NewShelf int, OldISBN varchar(20), OldPrice decimal, OldShelf int, ArchivedAt datetime2) CREATE TABLE Book( ISBN varchar(20) PRIMARY KEY, Price decimal, Shelf int) CREATE TABLE WeeklyChange( ISBN varchar(20) PRIMARY KEY, Price decimal, Shelf int) CREATE TABLE BookHistory( Action nvarchar(10), NewISBN varchar(20), NewPrice decimal, NewShelf int, OldISBN varchar(20), OldPrice decimal, OldShelf int, ArchivedAt datetime2)
SQL Server 2008 Merge语句的OUTPUT功能的SQL语句为
view plaincopy to clipboardprint MERGE Book AS B USING WeeklyChange AS WC ON B.ISBN = WC.ISBN WHEN MATCHED AND (B.Price <> WC.Price OR B.Shelf <> WC.Shelf) THEN UPDATE SET B.Price = WC.Price, B.Shelf = WC.Shelf WHEN NOT MATCHED THEN INSERT VALUES(WC.ISBN, WC.Price, WC.Shelf) OUTPUT $action, inserted.*, deleted.*, SYSDATETIME() INTO BookHistory; MERGE Book AS B USING WeeklyChange AS WC ON B.ISBN = WC.ISBN WHEN MATCHED AND (B.Price <> WC.Price OR B.Shelf <> WC.Shelf) THEN UPDATE SET B.Price = WC.Price, B.Shelf = WC.Shelf WHEN NOT MATCHED THEN INSERT VALUES(WC.ISBN, WC.Price, WC.Shelf) OUTPUT $action, inserted.*, deleted.*, SYSDATETIME() INTO BookHistory;
结果集为：
SELECT * FROM BookHistory GO Action NewISBN NewPrice NewShelf OldISBN OldPrice OldShelf ArchivedAt UPDATE A 101 1 A 100 1 2007-11-25 14:47:23.9907552 INSERT C 300 3 NULL NULL NULL 2007-11-25 14:47:23.9907552
这里有Insert和Update两种Output情况。假如只需要其中一种，可以用下面这种方法过滤：
view plaincopy to clipboardprint INSERT INTO Book(ISBN, Price, Shelf, ArchivedAt) SELECT ISBN, Price, Shelf, GETDATE() FROM (MERGE Book AS B USING WeeklyChange AS WC ON B.ISBN = WC.ISBN AND B.ArchivedAt IS NULL WHEN MATCHED AND (B.Price <> WC.Price OR B.Shelf <> WC.Shelf) THEN UPDATE SET Price = WC.Price, Shelf = WC.Shelf WHEN NOT MATCHED THEN INSERT VALUES(WC.ISBN, WC.Price, WC.Shelf, NULL) OUTPUT $action, WC.ISBN, Deleted.Price, Deleted.Shelf ) CHANGES(Action, ISBN, Price, Shelf) WHERE Action = 'UPDATE';
以上的相关内容就是对SQL Server 2008 Merge语句的OUTPUT功能的介绍，望你能有所收获。