/**
  * Update
  * 
  * Method is the base update function for this object class
  * 
  * @return string
  */
 function _update($properties = null)
 {
     //reasons to return
     if (is_null($properties)) {
         return false;
     }
     //building the query
     $query = "UPDATE `" . $this->_tbl . "_cstm`" . " SET ";
     //Updating the class property values
     foreach ($properties as $property => $value) {
         if ($property == 'id') {
             continue;
         }
         //Making sure that system properties are also set
         switch ($property) {
             case 'id_c':
                 break;
             case 'date_created':
                 break;
             case 'date_modified':
                 $date =& eFactory::getDate(time());
                 $query .= " `date_modified` = '" . $date->toMySQL() . "',";
                 break;
             default:
                 $query .= " `" . $property . "` = '" . $value . "',";
                 break;
         }
     }
     $query = substr($query, 0, strlen($query) - 1);
     $query .= " WHERE `id_c` = '" . $this->id . "';";
     if ($this->query($query)) {
         return $this->id;
     }
     return false;
 }