InnoDB插入会以静默方式失败，当表是MyISAM时可以正常工作

CREATE TABLE `products_vendors` (
`vendor_id` int(10) unsigned NOT NULL,
`product_id` int(10) unsigned NOT NULL,
`original_quantity` smallint(6) unsigned NOT NULL,
`quantity` smallint(5) unsigned NOT NULL,
`price` decimal(19,8) NOT NULL,
`created` int(10) unsigned NOT NULL,
`valid_until` int(10) unsigned NOT NULL,
PRIMARY KEY  (`vendor_id`,`product_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

$insert_sql = \"insert into products_vendors (\";
$insert_sql.= \"`vendor_id`,\";
$insert_sql.= \"`product_id`,\";
$insert_sql.= \"`original_quantity`,\";
$insert_sql.= \"`quantity`,\";
$insert_sql.= \"`price`,\";
$insert_sql.= \"`created`,\";
$insert_sql.= \"`valid_until` \";
$insert_sql.= \") values (\";
$insert_sql.= \"\'1\', \'2\', \'3\', \'4\', \'5\', \'6\', \'7\');\";

$db = new PDO(\"mysql:host=\" . DB_HOST . \";dbname=\" . DB_NAME, DB_USER, DB_PASSWORD, array(PDO::ATTR_PERSISTENT, true));
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$st = $db->prepare($insert_sql);
$st->execute();