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', 'k1lnkf3ajh66ia5b547usdlpk4', '216.73.216.72', '1787211352', '1787211352', '/shop_content.php?XTCsid=81fba26e1f006e30d12d9ee4d58a4030&coID=1')

[XT SQL Error]