1. mysql> ALTER TABLE `ports_fdb` CHANGE `created_at` `created_at` timestamp NULL ;
2. ERROR 1054 (42S22): Unknown column 'created_at' in 'ports_fdb'
3. mysql> describe ports_fdb;
4. +--------------+---------------------+------+-----+---------+----------------+
5. | Field        | Type                | Null | Key | Default | Extra          |
6. +--------------+---------------------+------+-----+---------+----------------+
7. | ports_fdb_id | bigint(20) unsigned | NO   | PRI | NULL    | auto_increment |
8. | port_id      | int(10) unsigned    | NO   | MUL | NULL    |                |
9. | mac_address  | varchar(32)         | NO   | MUL | NULL    |                |
10. | vlan_id      | int(10) unsigned    | NO   | MUL | NULL    |                |
11. | device_id    | int(10) unsigned    | NO   | MUL | NULL    |                |
12. +--------------+---------------------+------+-----+---------+----------------+
13. 5 rows in set (0.00 sec)
14.