text: -- serial_numbers --
  SET SESSION sql_mode="NO_AUTO_CREATE_USER";
  CREATE TABLE `phppos_items_serial_numbers` (
    `id` int(10) NOT NULL AUTO_INCREMENT,
    `item_id`  int(10) NOT NULL,
    `serial_number` varchar(255) COLLATE utf8_unicode_ci DEFAULT NULL,
    `unit_price` DECIMAL(23,10) NULL DEFAULT NULL,
    UNIQUE KEY `serial_number` (`serial_number`),
    PRIMARY KEY (`id`),
    CONSTRAINT `phppos_items_serial_numbers_ibfk_1` FOREIGN KEY (`item_id`) REFERENCES `phppos_items` (`item_id`)
  ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
  