title: update without select active record yii
body: <p>I try update num_of_gifts without select use yii active record and CDbCriteria
  this is my code:</p>
  
  <pre><code>$attributes = array('num_of_gifts' =&gt; 'num_of_gifts'+1);
  $condition = 'bla bla';
  $params = array(bla bla);
  Gifts::model()-&gt;updateAll($attributes, $condition, $params);
  </code></pre>
  
  <p>all I get that "1" at the num_of_gifts cell, 
  is it possible increase 1 to num_of_gifts? or I need select the amount of num_of_gifts and after it use update?</p>