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', '479lqb71m6tvj24k725nvcqhh3', '216.73.216.113', '1752884272', '1752884272', '/shop_content.php?coID=7&XTCsid=1455d70b156c4853db961f68b595bbe7')

[XT SQL Error]