title: Yii Select Using Custom Field
body: <p>Im trying to use a custom field to create another custom field, but Im getting error.
  I created that sample code to be easier to understand.</p>
  
  <p>Model.php:</p>
  
  <pre><code>public custom1;
  public custom2;
  </code></pre>
  
  <p>Example Code:</p>
  
  <pre><code>...
  $criteria-&gt;select=array("'custom1' AS custom1, CONCAT('variable: ', custom1) AS custom2");
  ...
  </code></pre>
  
  <p>Error:</p>
  
  <pre><code>SQLSTATE[42S22]: Column not found: 1054 Unknown column 'custom1' in 'field list'. 
  </code></pre>