CREATE TABLE `tiles` (
`id` int UNSIGNED NOT NULL,
`world_id` TINYINT(2) UNSIGNED NOT NULL DEFAULT 0,
`house_id` int UNSIGNED NOT NULL,
`x` int(5) UNSIGNED NOT NULL,
`y` int(5) UNSIGNED NOT NULL,
`z` TINYINT(2) UNSIGNED NOT NULL,
UNIQUE (`id`, `world_id`),
KEY (`x`, `y`, `z`),
FOREIGN KEY (`house_id`, `world_id`) REFERENCES `houses`(`id`, `world_id`) ON DELETE CASCADE
) ENGINE=InnoDB;