1366 - Incorrect integer value: '' for column 'customer_id' at row 1

insert into whos_online (customer_id, full_name, session_id, ip_address, time_entry, time_last_click, last_page_url) values ('', 'Guest', '54a519c9e236a981457c0bec101212a6', '216.73.216.52', '1759534641', '1759534641', '/shop/product_info.php?XTCsid=041c8fc0413f2441df67fe52a6815a15&info=p125_.html')

[XT SQL Error]