SQLServer中MERGE语句的使用

[ WITH <common_table_expression> [,...n] ]
MERGE
    [ TOP ( expression ) [ PERCENT ] ]
    [ INTO ] <target_table> [ WITH ( <merge_hint> ) ] [ [ AS ] table_alias ]
    USING <table_source> [ [ AS ] table_alias ]
    ON <merge_search_condition>
    [ WHEN MATCHED [ AND <clause_search_condition> ]
        THEN <merge_matched> ] [ ...n ]
    [ WHEN NOT MATCHED [ BY TARGET ] [ AND <clause_search_condition> ]
        THEN <merge_not_matched> ]
    [ WHEN NOT MATCHED BY SOURCE [ AND <clause_search_condition> ]
        THEN <merge_matched> ] [ ...n ]
    [ <output_clause> ]
    [ OPTION ( <query_hint> [ ,...n ] ) ]
;

<target_table> ::=
{
    [ database_name . schema_name . | schema_name . ] [ [ AS ] target_table ]
    | @variable [ [ AS ] target_table ]
    | common_table_expression_name [ [ AS ] target_table ]
}

<merge_hint>::=
{
    { [ <table_hint_limited> [ ,...n ] ]
    [ [ , ] { INDEX ( index_val [ ,...n ] ) | INDEX = index_val }]
    }
}

<merge_search_condition> ::=
    <search_condition>

<merge_matched>::=
    { UPDATE SET <set_clause> | DELETE }

<merge_not_matched>::=
{
    INSERT [ ( column_list ) ]
        { VALUES ( values_list )
        | DEFAULT VALUES }
}

<clause_search_condition> ::=
    <search_condition>

CREATE TABLE T_UnitMeasure(UnitMeasureCode  NCHAR(8),NameInfo NVARCHAR(25));
INSERT INTO T_UnitMeasure VALUES(N'Car00001',N'问界M5'),(N'Car00004',N'问界M9');
SELECT * FROM T_UnitMeasure;

DECLARE @SummaryOfChanges TABLE(Change VARCHAR(20));  
  
MERGE INTO T_UnitMeasure AS Target  
USING (VALUES (N'Car00001',N'问界M9'), (N'Car00002',N'坦克700'), (N'Car00003',N'奔驰大G500'))  
       AS Source (NewCode, NewNameInfo)  
ON Target.UnitMeasureCode = Source.NewCode  
WHEN MATCHED THEN  
  UPDATE SET NameInfo = Source.NewNameInfo  
WHEN NOT MATCHED BY TARGET THEN  
  INSERT (UnitMeasureCode, NameInfo) VALUES (NewCode, NewNameInfo)  
OUTPUT $action INTO @SummaryOfChanges;  
  
-- Query the results of the table variable.  
SELECT Change, COUNT(*) AS CountPerChange  
FROM @SummaryOfChanges  
GROUP BY Change;

CREATE PROCEDURE dbo.InsertUnitMeasure(@UnitMeasureCode NCHAR(8), @NameInfo NVARCHAR(25))
AS
BEGIN
    SET NOCOUNT ON;

    -- Update the row if it exists.
    UPDATE T_UnitMeasure
    SET NameInfo = @NameInfo
    WHERE UnitMeasureCode = @UnitMeasureCode

    -- Insert the row if the UPDATE statement failed.
    IF (@@ROWCOUNT = 0)
    BEGIN
        INSERT INTO T_UnitMeasure (UnitMeasureCode,NameInfo) VALUES (@UnitMeasureCode, @NameInfo)
    END
END;
GO
-- Test the procedure and return the results.
EXEC InsertUnitMeasure @UnitMeasureCode = 'Car00003', @NameInfo = N'奔驰E300L';

SELECT * FROM T_UnitMeasure;

UnitMeasureCode NameInfo
--------------- -------------------------
Car00001        问界M9
Car00004        问界M9
Car00002        坦克700
Car00003        奔驰E300L

(4 行受影响)

-- 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(8),
    ExistingName NVARCHAR(50),
    ActionTaken NVARCHAR(10),
    NewCode NCHAR(8),
    NewName NVARCHAR(50),
);
GO

DROP TABLE #MyTempTable

ALTER PROCEDURE dbo.InsertUnitMeasure (@UnitMeasureCode NCHAR(8), @NameInfo NVARCHAR(25))
AS
BEGIN
    SET NOCOUNT ON;

    MERGE T_UnitMeasure AS tgt
    USING (SELECT @UnitMeasureCode, @NameInfo) AS src (UnitMeasureCode, NameInfo)
        ON (tgt.UnitMeasureCode = src.UnitMeasureCode)
    WHEN MATCHED THEN
      UPDATE SET NameInfo = src.NameInfo
    WHEN NOT MATCHED BY TARGET THEN
      INSERT (UnitMeasureCode,NameInfo) VALUES (@UnitMeasureCode, @NameInfo)
    OUTPUT deleted.*,
        $action,
        inserted.*
    INTO #MyTempTable;
END;
GO
-- Test the procedure and return the results.
EXEC InsertUnitMeasure @UnitMeasureCode = 'Car00001', @NameInfo = N'问界M7';
EXEC InsertUnitMeasure @UnitMeasureCode = 'Car00002', @NameInfo = N'丰田皇冠';
EXEC InsertUnitMeasure @UnitMeasureCode = 'Car00005', @NameInfo = N'宝马X5';


SELECT * FROM #MyTempTable;

ExistingCode ExistingName       ActionTaken NewCode        NewName
------------ ------------------ --------    -----------  ---------- 
Car00001     问界M9               UPDATE      Car00001 		问界M7
Car00002     坦克700              UPDATE      Car00002 		丰田皇冠
NULL         NULL                INSERT      Car00005 		宝马X5
(3 行受影响)

SELECT * FROM T_UnitMeasure;

UnitMeasureCode NameInfo
--------------- -------------------------
Car00001        问界M7
Car00004        问界M9
Car00002        丰田皇冠
Car00003        奔驰E300L
Car00005        宝马X5

(5 行受影响)

SELECT * FROM T_UnitMeasure

UnitMeasureCode NameInfo
--------------- -------------------------
Car00001        问界M7
Car00004        问界M9
Car00002        丰田皇冠
Car00003        奔驰E300L
Car00005        宝马X5

(5 行受影响)
-- 更新及删除
MERGE T_UnitMeasure AS Target
USING (VALUES (N'Car00001',N'问界M5'), (N'Car00004',N'问界M9'))  
       AS Source (NewCode, NewNameInfo)  
ON Target.UnitMeasureCode = Source.NewCode  
WHEN MATCHED AND Target.NameInfo=Source.NewNameInfo THEN
  DELETE
WHEN MATCHED THEN
  UPDATE SET NameInfo = Source.NewNameInfo
OUTPUT $action,
    Inserted.UnitMeasureCode,
    Inserted.NameInfo,
    Deleted.UnitMeasureCode,
    Deleted.NameInfo;

$action    UnitMeasureCode NameInfo                  UnitMeasureCode NameInfo
---------- --------------- ------------------------- --------------- -------------------------
UPDATE     Car00001        问界M5                      Car00001        问界M7
DELETE     NULL            NULL                      Car00004        问界M9

(2 行受影响)

SELECT * FROM T_UnitMeasure

UnitMeasureCode NameInfo
--------------- -------------------------
Car00001        问界M5
Car00002        丰田皇冠
Car00003        奔驰E300L
Car00005        宝马X5

(4 行受影响)

CREATE TABLE T_UnitMeasure_list 
( ID BIGINT IDENTITY(1,1) PRIMARY KEY, 
  UnitMeasureCode  NCHAR(8),
  NameInfo NVARCHAR(25),
  Action NVARCHAR(16),
  UnitMeasureCode_old NCHAR(8),
  NameInfo_old  NVARCHAR(25),
);
GO

INSERT INTO T_UnitMeasure_list
SELECT UnitMeasureCode,NameInfo,Action,UnitMeasureCode_old,NameInfo_old
FROM (
    MERGE T_UnitMeasure AS pi
    USING (VALUES (N'Car00005',N'宝马X5'), (N'Car00001',N'问界M9'))  AS src (NewCode, NewNameInfo) 
        ON pi.UnitMeasureCode = src.NewCode
    WHEN MATCHED AND pi.NameInfo=src.NewNameInfo THEN 
      DELETE
	WHEN MATCHED THEN
	  UPDATE SET pi.NameInfo = src.NewNameInfo
    OUTPUT $action,
        Inserted.UnitMeasureCode,
        Inserted.NameInfo,
        Deleted.UnitMeasureCode AS UnitMeasureCode_old,
        Deleted.NameInfo AS NameInfo_old
    ) AS Changes(Action, UnitMeasureCode,NameInfo, UnitMeasureCode_old, NameInfo_old)
;
GO

SELECT * FROM T_UnitMeasure_list;

ID                   UnitMeasureCode NameInfo                  Action           UnitMeasureCode_old NameInfo_old
-------------------- --------------- ------------------------- ---------------- ------------------- -------------------------
1                    Car00001        问界M9                      UPDATE           Car00001            问界M5
2                    NULL            NULL                        DELETE           Car00005            宝马X5

(2 行受影响)

SELECT * FROM T_UnitMeasure;

UnitMeasureCode NameInfo
--------------- -------------------------
Car00001        问界M9
Car00002        丰田皇冠
Car00003        奔驰E300L

(3 行受影响)

-- CREATE node and edge tables
CREATE TABLE Person
(
    ID INTEGER PRIMARY KEY,
    PersonName VARCHAR(100)
)
AS NODE
GO

CREATE TABLE City
(
    ID INTEGER PRIMARY KEY,
    CityName VARCHAR(100),
    StateName VARCHAR(100)
)
AS NODE
GO

CREATE TABLE livesIn
(
    StreetAddress VARCHAR(100)
)
AS EDGE
GO

-- INSERT some test data into node and edge tables
INSERT INTO Person VALUES (1, 'Ron'), (2, 'David'), (3, 'Nancy')
GO

INSERT INTO City VALUES (1, 'Redmond', 'Washington'), (2, 'Seattle', 'Washington')
GO

INSERT livesIn SELECT P.$node_id, C.$node_id, c
FROM Person P, City C, (values (1,1, '123 Avenue'), (2,2,'Main Street')) v(a,b,c)
WHERE P.id = a AND C.id = b
GO

-- Use MERGE to update/insert edge data
CREATE OR ALTER PROCEDURE mergeEdge
    @PersonId integer,
    @CityId integer,
    @StreetAddress varchar(100)
AS
BEGIN
    MERGE livesIn
        USING ((SELECT @PersonId, @CityId, @StreetAddress) AS T (PersonId, CityId, StreetAddress)
                JOIN Person ON T.PersonId = Person.ID
                JOIN City ON T.CityId = City.ID)
        ON MATCH (Person-(livesIn)->City)
    WHEN MATCHED THEN
        UPDATE SET StreetAddress = @StreetAddress
    WHEN NOT MATCHED THEN
        INSERT ($from_id, $to_id, StreetAddress)
        VALUES (Person.$node_id, City.$node_id, @StreetAddress) ;
END
GO

-- Following will insert a new edge in the livesIn edge table
EXEC mergeEdge 3, 2, '4444th Avenue'
GO

-- Following will update the StreetAddress on the edge that connects Ron to Redmond
EXEC mergeEdge 1, 1, '321 Avenue'
GO

-- Verify that all the address were added/updated correctly
SELECT PersonName, CityName, StreetAddress
FROM Person , City , livesIn
WHERE MATCH(Person-(livesIn)->city)
GO