public function execute()
 {
     try {
         $fields = array(pVentaTableClass::ID, pVentaTableClass::FECHA, pVentaTableClass::USUARIO_ID);
         $this->objPventa = pVentaTableClass::getAll($fields, false);
         $this->defineView('index', 'pVenta', session::getInstance()->getFormatOutput());
     } catch (PDOException $exc) {
         echo $exc->getMessage();
         echo '<br>';
         echo '<pre>';
         print_r($exc->getTrace());
         echo '</pre>';
     }
 }