What happens if the column is, and remains, NULL? Or if it's being updated from NULL to a value? Many addresses won't have an address2/3, and that could be null in both the inserted and deleted tables. Or it could be changed from NULL to a value due to running the address through an address verification routine for getting cheaper mailing rates (CASS).

Another potential issue: do you want the date updated if the case of the field is changed, and that's the only change? To handle this, you'll need to deal with case sensitive collations.

Here's an example that shows the NULL issue. Just use the remarked out lines in the trigger to handle them being updated.

SET NOCOUNT ON;

if OBJECT_ID('dbo.Test') IS NOT NULL DROP TABLE dbo.Test;

GO

CREATE TABLE dbo.Test (

RowID int PRIMARY KEY CLUSTERED,

Address1 varchar(50) NULL,

Address2 varchar(50) NULL,

Address3 varchar(50) NULL,

Address1Date datetime NULL,

Address2Date datetime NULL,

Address3Date datetime NULL);

GO

CREATE TRIGGER TestDates

ON dbo.Test

AFTER UPDATE

AS

BEGIN

SET NOCOUNT ON;

UPDATE dbo.Test

SET Address1Date = GetDate()

FROM dbo.Test

JOIN inserted i

ON i.RowID = Test.RowID

JOIN deleted d

ON d.RowID = Test.RowID

WHERE i.Address1 <> d.Address1

-- OR (d.Address1 IS NULL AND i.Address1 IS NOT NULL);

UPDATE dbo.Test

SET Address2Date = GetDate()

FROM dbo.Test

JOIN inserted i

ON i.RowID = Test.RowID

JOIN deleted d

ON d.RowID = Test.RowID

WHERE i.Address2 <> d.Address2

-- OR (d.Address2 IS NULL AND i.Address2 IS NOT NULL);

UPDATE dbo.Test

SET Address3Date = GetDate()

FROM dbo.Test

JOIN inserted i

ON i.RowID = Test.RowID

JOIN deleted d

ON d.RowID = Test.RowID

WHERE i.Address3 <> d.Address3

-- OR (d.Address3 IS NULL AND i.Address3 IS NOT NULL);

END;

GO

INSERT INTO dbo.Test

SELECT 1, 'TEST ADDRESS 1', NULL, NULL, NULL, NULL, NULL UNION ALL

SELECT 2, 'Test Address 2', 'Test2', NULL, NULL, NULL, NULL UNION ALL

SELECT 3, 'Test Address 3', 'Test3', 'Test3', NULL, NULL, NULL;

-- show updating case doesn't put dates into the table

SELECT * FROM dbo.Test;

UPDATE dbo.Test

SET Address1 = UPPER(Address1),

Address2 = UPPER(Address2),

Address3 = UPPER(Address3);

SELECT * FROM dbo.Test;

-- show effect of updating a field from NULL to a value

UPDATE dbo.Test

SET Address3 = 'MyTest'

WHERE Address3 IS NULL;

SELECT * FROM dbo.Test;