title: Updating a row with a trigger without causing an infinite loop
body: <p>I have a column called <code>updated</code> which is intended to show the last time that column was altered.</p>
  
  <p>My first attempt at this was to create a trigger that changed the <code>updated</code> column to the value returned by <code>now()</code>. But because this trigger happens on an update event, it caused an infinite loop (updating the updated column causes the trigger to fire).</p>
  
  <p>I also tried implementing a rule to do this with similar effects. </p>
  
  <p>I can't imagine that this is something I am forced to do on the application layer when ever I call and update function. So how can I update that row's updated column without causing infinite loops?</p>