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', 'm885m81k2k0vm6bki59vqjm6j6', '216.73.216.180', '1766944886', '1766944886', '/popup_content.php?XTCsid=ee199fdb171da456469b100b0e4b3f11&coID=1')

[XT SQL Error]