title: Updating the upper bound of a daterange to infinity
body: <p>The syntax of how to update just the upper bound of a daterange column has me stumped.</p>
  
  <p>I would like the lower bound to remain unchanged and to update only the upper bound of a daterange column (e.g. timespan)to 'infinity' if it contains a certain bound (e.g. 2013-12-31).</p>
  
  <p>This is as far as i have gotten:</p>
  
  <pre><code>UPDATE table
  SET timespan = daterange(lower(timespan),upper(infinity)::daterange)
  WHERE (upper(timespan) = '2013-12-31'::daterange);
  </code></pre>