mysql> CREATE TABLE `message_folders` (
    ->   `id` int(11) NOT NULL auto_increment,
    ->   `name` varchar(255) NOT NULL,
    ->   `created_at` datetime NOT NULL,
    ->   PRIMARY KEY  (`id`)
    -> ) ENGINE=InnoDB DEFAULT CHARSET=latin1;
ERROR 1050 (42S01): Table 'message_folders' already exists
mysql> describe message_folders;
+------------+--------------+------+-----+---------------------+----------------+
| Field      | Type         | Null | Key | Default             | Extra          |
+------------+--------------+------+-----+---------------------+----------------+
| id         | int(11)      |      | PRI | NULL                | auto_increment |
| name       | varchar(255) |      |     |                     |                |
| created_at | datetime     |      |     | 0000-00-00 00:00:00 |                |
+------------+--------------+------+-----+---------------------+----------------+
3 rows in set (0.00 sec)

mysql> insert into message_folders (id, name, created_at) values (1, null, null);
ERROR 1048 (23000): Column 'name' cannot be null
mysql> insert into message_folders (id) values (1);
Query OK, 1 row affected (0.07 sec)