SQL Server 2008新特性 Merge 详细见联机手册

USE AdventureWorks2008R2;
GO
CREATE PROCEDURE dbo.InsertUnitMeasure
    @UnitMeasureCode nchar(3),
    @Name nvarchar(25)
AS 
BEGIN
    SET NOCOUNT ON;
-- Update the row if it exists.    
    UPDATE Production.UnitMeasure
    SET Name = @Name
    WHERE UnitMeasureCode = @UnitMeasureCode
-- Insert the row if the UPDATE statement failed.    
    IF (@@ROWCOUNT = 0 )
    BEGIN
        INSERT INTO Production.UnitMeasure (UnitMeasureCode, Name)
        VALUES (@UnitMeasureCode, @Name)
    END
END;
GO
-- Test the procedure and return the results.
EXEC InsertUnitMeasure @UnitMeasureCode = 'ABC', @Name = 'Test Value';
SELECT UnitMeasureCode, Name FROM Production.UnitMeasure
WHERE UnitMeasureCode = 'ABC';
GO

-- Rewrite the procedure to perform the same operations using the MERGE statement.
-- Create a temporary table to hold the updated or inserted values from the OUTPUT clause.
CREATE TABLE #MyTempTable
    (ExistingCode nchar(3),
     ExistingName nvarchar(50),
     ExistingDate datetime,
     ActionTaken nvarchar(10),
     NewCode nchar(3),
     NewName nvarchar(50),
     NewDate datetime
    );
GO
ALTER PROCEDURE dbo.InsertUnitMeasure
    @UnitMeasureCode nchar(3),
    @Name nvarchar(25)
AS 
BEGIN
    SET NOCOUNT ON;
           
    MERGE Production.UnitMeasure AS target
    USING (SELECT @UnitMeasureCode, @Name) AS source (UnitMeasureCode, Name)
    ON (target.UnitMeasureCode = source.UnitMeasureCode)
    WHEN MATCHED THEN 
        UPDATE SET Name = source.Name
    WHEN NOT MATCHED THEN    
        INSERT (UnitMeasureCode, Name)
        VALUES (source.UnitMeasureCode, source.Name)
        OUTPUT deleted.*, $action, inserted.* INTO #MyTempTable;
END;
GO
-- Test the procedure and return the results.
EXEC InsertUnitMeasure @UnitMeasureCode = 'ABC', @Name = 'New Test Value';
EXEC InsertUnitMeasure @UnitMeasureCode = 'XYZ', @Name = 'Test Value';
EXEC InsertUnitMeasure @UnitMeasureCode = 'ABC', @Name = 'Another Test Value';

SELECT * FROM #MyTempTable;
-- Cleanup 
DELETE FROM Production.UnitMeasure WHERE UnitMeasureCode IN ('ABC','XYZ');
DROP TABLE #MyTempTable;
GO