获取每个人每天的最小时间记录

CREATE TABLE IF NOT EXISTS `accesscards` (
    `id` int(11) NOT NULL AUTO_INCREMENT,
    `department` varchar(255) NOT NULL,
    `name` varchar(255) NOT NULL,
    `entrydates` datetime NOT NULL, PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1 AUTO_INCREMENT=1 ;

INSERT INTO `accesscards` (`id`, `department`, `name`, `entrydates`) VALUES
(1, 'test', 't1', '2013-12-06 16:10:00'),
(2, 'test', 't1', '2013-12-06 15:10:00'),
(3, 'test', 't1', '2013-12-07 15:11:00'),
(4, 'test', 't1', '2013-12-07 15:24:00'),
(5, 'test', 't2', '2013-12-06 16:10:00'),
(6, 'test', 't2', '2013-12-06 16:25:00'),
(7, 'test', 't2', '2013-12-07 15:59:00'),
(8, 'test', 't2', '2013-12-07 16:59:00');
CREATE TABLE IF NOT EXISTS `accesscards` (