Help on some SQL command...

Hello to all the SQL gurus...

I have this little table:

test1 (
id char(8) primary key,
name char(20),
create_date timestamp
);

Now, the create_date need to be updated
to date and time whenever id is being
inserted or updated.

Is there a way in SQL that I can do this
automatically?

I try the following command using 'trigger'

----
CREATE_TRIGGER test1_autodate
AFTER INSERT OR UPDATE ON
test1 FOR EACH ROW EXECUTE update("test1")

CREATE FUNCTION update(char *) RETURNS int4
AS 'UPDATE $1 set date="now"'
LANGUAGE 'sql';
----

But realized 'char *' is not allow... Is there a
way to solve this?

Or Am I the right track in solving this problem?

Hope someone can help me... thanks.

Sei Heng