CREATE TABLE `table1` (
        ......
        `property_id` int(8) REFERENCES `table2` (id) ON UPDATE CASCADE ON DELETE NO ACTION,
        ......
    ) ENGINE=InnoDB;

    CREATE TABLE `table2` (
        `id` int(8) PRIMARY KEY AUTO_INCREMENT NOT NULL,
        `property` varchar(50)
    ) ENGINE=InnoDB;

##</code><code>##

    my ($pid) = $db->query(<<END_SQL, $property)->list;

    SELECT `id` FROM `table2` WHERE `property` = ?

END_SQL

    if (not $pid) {
        $db->query("INSERT INTO `table2` (`property`) VALUES (?)", $property);
        $pid = $db->last_insert_id();
    }