Output row values effected by an update

Have you ever thought about logging the before and after value for an update or delete? It’s actually pretty simple getting these information as a return on an update and delete.

Lets make a quick example.

First we need to create a test table an populate a couple of rows for testing purpose.

CREATE TABLE Person
(
    PersonID INT IDENTITY(1,1) PRIMARY KEY,
    Name VARCHAR(100)
)

INSERT INTO Person (Name) VALUES ('Peter')
INSERT INTO Person (Name) VALUES ('Jens')
INSERT INTO Person (Name) VALUES ('Jacob')
INSERT INTO Person (Name) VALUES ('Morten')

SELECT * FROM Person

Now lets change the second row. The update we are using are changing the name from Jens to Jens Jensen and returning both the new (Jens Jensen) and the old name (Jens).

UPDATE Person
SET        Name = 'Jens Jensen'
OUTPUT  inserted.Name AS NewName, 
        deleted.Name AS OldName
WHERE    Name = 'Jens'

As you can see the keyword output return inserted and deleted values.

You can also use OUTPUT as a part of a DELETE statement. Combined with some extra TSQL commands you have a perfect output for a Log table.

DELETE    FROM Person
OUTPUT    deleted.PersonID AS DeletedPersonID, deleted.Name AS DeletedPersonName,
        SYSTEM_USER AS DeletedBy, SYSDATETIME() AS DeleteTime
WHERE    Name = 'Peter'

Enjoy