日期
常见日期类型：
| 类型 | 占用字节 | 表示范围 |
|---|---|---|
| DATETIME | 8 | 1000-01-01 00:00:00 ~ 9999:12:31 23:59:59 |
| TIMESTAMP | 4 | 1970-01-01 00:00:00 UTC ~ 2038-01-19 03:14:07 UTC |
mysql> create table test(
a bigint not null auto_increment primary key,
b int not null,
addTime timestamp not null default current_timestamp,
updateTime datetime not null default current_timestamp on update current_timestamp);