SQLServer 2008 Merge語句的OUTPUT功能

2024-08-31 01:00:49

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下面介紹一下把Output同2008的新T-SQL語句Merge組合使用的方法：
新建下面表：

復制代碼代碼如下:

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語句為

復制代碼代碼如下:

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;

結果集為：

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

這里有Insert和Update兩種Output情況。如果只需要其中一種，可以用下面這種方法過濾：

復制代碼代碼如下:

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';