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', 'bhcch436gei4mvlv28lhqdvr51', '216.73.216.63', '1774092560', '1774092560', '/shop_content.php?XTCsid=85f438a686cbfb5e3ea5e5d6b9611958&coID=1')

[XT SQL Error]