CREATE TABLE `t1` (
  `id` int(3) NOT NULL AUTO_INCREMENT,
  `dtime` date DEFAULT NULL,
  `ttime` time DEFAULT NULL,
  PRIMARY KEY (`id`)
);
/* вам надо mydate, я для проверки продублировал и dtime, ttime */
CREATE TABLE `t2` (
  `id` int(3) NOT NULL AUTO_INCREMENT,
  `mydate` datetime DEFAULT NULL,
  `dtime` date DEFAULT NULL,
  `ttime` time DEFAULT NULL,
  PRIMARY KEY (`id`)
);

DELIMITER $$
CREATE TRIGGER `test`.`tr_aft_ins_t1` AFTER INSERT ON `test`.`t1`
    FOR EACH ROW BEGIN
	INSERT INTO t2(mydate,dtime,ttime) VALUES
	(CAST(CONCAT(NEW.dtime,' ', NEW.ttime) AS DATETIME), new.dtime,new.ttime);
    END$$
DELIMITER ;
INSERT INTO t1 VALUES(NULL, '2006-11-11','12:12:12'),(NULL, '2015-09-09','02:02:02');