change the date column to be a timestamp instead:
CREATE TABLE `abc` (
  `id_abc` int(11) NOT NULL AUTO_INCREMENT,
  `fecha` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
  `abc` varchar(255) NOT NULL,
  `comentarios` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id_abc`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8


