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