INSERT .. ON DUPLICATE KEY UPDATE does not update

CREATE TABLE `v` (

  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,

  PRIMARY KEY (`id`)

) ENGINE=MYISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

INSERT v values (1);

CREATE TABLE `vp` (

  `id` int(11) unsigned NOT NULL AUTO_INCREMENT,

  `v_id` int(10) unsigned NOT NULL,

  `p_id` int(10) unsigned NOT NULL,

  `ppp` varchar(255) NOT NULL,

  PRIMARY KEY (`id`),

  UNIQUE KEY `IDX_vp_uniq` (`v_id`,`p_id`),

  KEY `FK_vp_v` (`v_id`)

) ENGINE=MYISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

INSERT vp VALUES (12, 1, 100, 'text12');

INSERT INTO `vp` (`id`,`ppp`) VALUES (12, 'test12-2') ON DUPLICATE KEY UPDATE `ppp` = VALUES(`ppp`);

SELECT * FROM vp;

DROP TABLE vp, v;

REATE TABLE `v` (

`id` int(11) unsigned NOT NULL AUTO_INCREMENT,

PRIMARY KEY (`id`)

) ENGINE=MYISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

INSERT v values (1);

CREATE TABLE `vp` (

`id` int(11) unsigned NOT NULL AUTO_INCREMENT,

`v_id` int(10) unsigned NOT NULL,

`p_id` int(10) unsigned NOT NULL,

`ppp` varchar(255) NOT NULL,

PRIMARY KEY (`id`),

UNIQUE KEY `IDX_vp_uniq` (`v_id`,`p_id`),

KEY `FK_vp_v` (`v_id`)

) ENGINE=MYISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8;

INSERT vp VALUES (12, 1, 100, 'text12');

INSERT INTO `vp` (`id`,`ppp`) VALUES (12, 'test12-2') ON DUPLICATE KEY UPDATE `ppp` = VALUES(`ppp`);

Warnings:

Warning	1364	Field 'v_id' doesn't have a default value

Warning	1364	Field 'p_id' doesn't have a default value

SELECT * FROM vp;

id	v_id	p_id	ppp

12	1	100	test12-2

DROP TABLE vp, v;