日期类型

1、作用：时间相关

2、分类：
date：1999-01-27
time: 11:11:11
datetime:1999-01-27 11:11:11
year:1999

3、测试
create table student(
    id int,
    name char(16),
    born_year year,
    birth date,
    class_time time,
    reg_time datetime
);

insert into student values(1,'egon','2000','2000-01-27','08:30:00','2013-11-11 11:11:11');