MySQL删除重复数据行,只保留一条
2015-10-12 22:16
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原文地址 : http://quqtalk.iteye.com/blog/2013602
Sql代码
delimiter $$
CREATE TABLE `devices_all` (
`device_all_id` int(11) NOT NULL AUTO_INCREMENT,
`device_id` varchar(512) DEFAULT NULL,
`device_token` varchar(512) DEFAULT NULL,
`client_agent` varchar(512) DEFAULT NULL,
`create_time` datetime DEFAULT NULL,
PRIMARY KEY (`device_all_id`)
) ENGINE=MyISAM AUTO_INCREMENT=49 DEFAULT CHARSET=latin1$$
表名devices_all,判重列device_id。
Sql代码
delete from devices_all
where device_id in (select device_id from (select device_id from devices_all a group by a.device_id having count(a.device_id) > 1) as a)
and device_all_id not in (select device_all_id from (select min( device_all_id) device_all_id from devices_all group by device_id having count( device_id)>1) as b)
Sql代码
delimiter $$
CREATE TABLE `devices_all` (
`device_all_id` int(11) NOT NULL AUTO_INCREMENT,
`device_id` varchar(512) DEFAULT NULL,
`device_token` varchar(512) DEFAULT NULL,
`client_agent` varchar(512) DEFAULT NULL,
`create_time` datetime DEFAULT NULL,
PRIMARY KEY (`device_all_id`)
) ENGINE=MyISAM AUTO_INCREMENT=49 DEFAULT CHARSET=latin1$$
Sql代码
delimiter $$
CREATE TABLE `devices_all` (
`device_all_id` int(11) NOT NULL AUTO_INCREMENT,
`device_id` varchar(512) DEFAULT NULL,
`device_token` varchar(512) DEFAULT NULL,
`client_agent` varchar(512) DEFAULT NULL,
`create_time` datetime DEFAULT NULL,
PRIMARY KEY (`device_all_id`)
) ENGINE=MyISAM AUTO_INCREMENT=49 DEFAULT CHARSET=latin1$$
表名devices_all,判重列device_id。
Sql代码
delete from devices_all
where device_id in (select device_id from (select device_id from devices_all a group by a.device_id having count(a.device_id) > 1) as a)
and device_all_id not in (select device_all_id from (select min( device_all_id) device_all_id from devices_all group by device_id having count( device_id)>1) as b)
Sql代码
delimiter $$
CREATE TABLE `devices_all` (
`device_all_id` int(11) NOT NULL AUTO_INCREMENT,
`device_id` varchar(512) DEFAULT NULL,
`device_token` varchar(512) DEFAULT NULL,
`client_agent` varchar(512) DEFAULT NULL,
`create_time` datetime DEFAULT NULL,
PRIMARY KEY (`device_all_id`)
) ENGINE=MyISAM AUTO_INCREMENT=49 DEFAULT CHARSET=latin1$$
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