语法是：

DROP TABLE IF EXISTS `nav_admin`;

CREATE TABLE `nav_admin`(

`id` int(10) NOT NULL AUTO_INCREMENT,

`username` VARCHAR(50) NOT NULL ,

`password` VARCHAR(50) NOT NULL ,

`addtime`  TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '创建时间' ,

`logintime` TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '登录时间' ,

`loginip` VARCHAR(20) ,

PRIMARY KEY(`id`)

)ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

运行时报错

[Err] 1293 - Incorrect table definition; there can be only one TIMESTAMP column with CURRENT_TIMESTAMP in DEFAULT or ON UPDATE clause

老师，应该如何设置一个表中两列时间轴