create table if not exists t_user (
	`id`       int  primary  key not null ,
	`username` char (50) not null,
	`pwd`      char(50) not null,
	`create_time` datetime not null,
	`update_time` datetime
) ;

create table if not exists vehicle (
    `id` int  primary  key not null ,
    `vin` char (50) not null,
    `total_mileage` int not null,
    `create_time` datetime not null
) ;