mysql 一些常用命令

一. alter
1. alter add:
alter table tablename add id int primary key not null auto_increment;
2.alter drop,alter change;

二. insert into
字段属性分别为DATE，TIME，TIMESTAMP：
1.DATE:
insert into riqi values(10000101);
2.TIME:
mysql> insert into shijian values(-8385959);
Query OK, 1 row affected (0.08 sec)
mysql> insert into shijian values(8385959);
Query OK, 1 row affected (0.13 sec)
不足7位数字就从右到左赋值 没有就赋0
mysql> insert into shijian values(159);
+————+
| 00:01:59 |
| 838:59:59 |
| -838:59:59 |
+————+
3.TIMESTAMP:
yyyymmddhhmmss、yymmddhhmmss、yyyymmdd或yymmdd格
mysql> insert into ts values(19700101080001);
mysql> insert into ts values(19700102);
mysql> insert into ts values(371231);
mysql> insert into ts values(1231);
自动补上0
+———————+
+———————+
| 1970-01-01 08:00:01 |
| 2037-12-31 23:59:59 |
| 1970-01-02 00:00:00 |
| 2037-01-02 00:00:00 |
| 2037-12-31 00:00:00 |
+———————+