Q:Update Rule

 I want  to save the user and date in a row when the user changed it.
If I use an update rule, how can I prevent a loop ?

Bad example:

create rule  r_changed
    as on update to requesttable
    do update requesttable
        set changed_by = current_user,
               date_of_last_change = current_date;


What is better ?


Detlef