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', 'eec75dug30omcu8kvn5p2mk144', '216.73.216.165', '1752305723', '1752305723', '/product_info.php?info=p16_Octoberfest-CD.html&XTCsid=81fba26e1f006e30d12d9ee4d58a4030')

[XT SQL Error]