public function selectAdd($k = null)
 {
     if (!isset($k)) {
         parent::selectAdd();
         $fields = $this->table();
         foreach ($fields as $field => $data_type) {
             if ($data_type & DB_DATAOBJECT_POINT || $data_type & DB_DATAOBJECT_LINE_STRING) {
                 parent::selectAdd("AsText(" . $field . ") as " . $field);
             } else {
                 parent::selectAdd($this->tableName() . "." . $field) . "as " . $field;
             }
         }
     } else {
         parent::selectAdd($k);
     }
 }