title: MySQL update enums
body: <p>I have a field with enums: 'preview','active','closed'</p>
  
  <p>When I query like this:</p>
  
  <pre><code>        $query = "UPDATE albums 
                  SET album_active = preview 
                  WHERE album_id = 3";
          $result = mysql_query($query);
          if (!$result) die('Invalid query: ' . mysql_error());
  </code></pre>
  
  <p>I get:</p>
  
  <p><code>Invalid query: Unknown column 'preview' in 'field list</code></p>
  
  <p>Other query:</p>
  
  <pre><code>        $query = sprintf("UPDATE albums SET 
                      album_active = %s 
                      WHERE album_id = %d", 
                      $_POST['album_active'], 
                      $_POST['album_id']
              );
  </code></pre>