From the article:

One might be tempted to think that we would just need to change the last_modified field at the end of the trigger with the actual time and date and the magic would be done. But it's not so simple! The normal triggers which are called AFTER Triggers do not allow you to change the data on the virtual tables. So SQL Server 2000 has extended the power of triggers by letting you create a second kind of trigger, called an INSTEAD OF.

The author states -correctly- that AFTER triggers don't allow modification of the virtual tables. But he goes on to suggest that such modification is allowed in an INSTEAD OF trigger. This is nonsense - as the code he posted proves, the changes are made to the base table, not to the virtual tables. That can be done from both an AFTER and an INSTEAD OF trigger.

Two weaknesses in the suggested code have already been pointed out: the code fails on multi-row updates; the revised code (posted up-thread) fails if the primary key is changed. Let me add a third: the use of proprietary T-SQL code where ANSI standard code works just as well.

CREATE TRIGGER TriggerName ON [Table_Name]

AFTER UPDATE

AS

   UPDATE [Table_Name]

      SET  last_modified = CURRENT_TIMESTAMP 'this will do the magic

   WHERE EXISTS

 (SELECT *

   FROM   inserted

   WHERE inserted.id = [Table_Name].id)

If the table has a multi-column key, simply extend the WHERE clause of the subquery to include all the columns in the key.

Best, Hugo