mysql-获取每个人每天的最小日期时间的记录

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');

上面是我的查询,我想获取一个人每天的记录.该记录应具有当天的最小日期时间.我需要该日期时间的完整记录

我的预期输出here

我尝试使用

SELECT id, MIN(entrydates) FROM accesscards WHERE 1=1 AND name!='' GROUP BY DATE(entrydates) ORDER BY id

但是对于“ t1”,我得到id = 1和第一行的输入日期.

请帮帮我.如果重复,则提供链接.

解决方法:

SELECT a1.*
FROM accesscards a1
JOIN (SELECT name, MIN(entrydates) mindate
      FROM accesscards
      WHERE name != ''
      GROUP BY name, date(entrydates)) a2
ON a1.name = a2.name AND a1.entrydates = a2.mindate

DEMO

标签：greatest-n-per-group,sql,mysql
来源： https://codeday.me/bug/20191122/2058087.html