MySQL删除重复数据行，只保留一条
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。
delete from devices_all
where device_id in (selectdevice_id from(select device_id fromdevices_allagroup 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 bydevice_id having count( device_id)>1) as b)
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