laravel 数据库 4 -- timestamp
20 March 2017

禁止自动更新 created_at, updated_at

public $timestamps = false;
$user->touch();                // 更新一个实例化的 model 的时间戳
protected $dateFormat = 'U';   // date() 函数的默认格式
class User extends Model {
    use SoftDeletes;
    protected $dates = ['created_at', 'updated_at', 'disabled_at']
}