is this 'normal' mysql behaviour? how didn't i notice this before?

wtf.sql

mysql> create table wtf ( id int not null auto_increment primary key, expletive varchar(64) not null, incredulity_level int not null, nullable int null );
Query OK, 0 rows affected (0.01 sec)


mysql> show create table wtf;
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table                                                                                                                                                                                                                                              |
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
| wtf   | CREATE TABLE `wtf` (
  `id` int(11) NOT NULL auto_increment,
  `expletive` varchar(64) NOT NULL,
  `incredulity_level` int(11) NOT NULL,
  `nullable` int(11) default NULL,
  PRIMARY KEY  (`id`)
) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=latin1 | 
+-------+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)


mysql> insert into wtf ( nullable ) values ( '42' );
Query OK, 1 row affected, 2 warnings (0.00 sec)

mysql> select * from wtf;
+----+-----------+-------------------+----------+
| id | expletive | incredulity_level | nullable |
+----+-----------+-------------------+----------+
|  1 |           |                 0 |       42 | 
+----+-----------+-------------------+----------+
1 row in set (0.00 sec)


Really?

Update, this is because MySQL isn't running in strict mode:

Strict mode controls how MySQL handles input values that are invalid or missing. A value can be invalid for several reasons. For example, it might have the wrong data type for the column, or it might be out of range. A value is missing when a new row to be inserted does not contain a value for a non-NULL column that has no explicit DEFAULT clause in its definition. (For a NULL column, NULL is inserted if the value is missing.)

See: http://dev.mysql.com/doc/refman/5.0/en/server-sql-mode.html#sqlmode_strict_all_tables