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', 'abfscki0f5qphl3tq02skph3u4', '216.73.216.70', '1752612448', '1752612448', '/product_info.php?info=p21_Paper-tablecloth-10-meters.html&XTCsid=6434a50ec6def965fd2bb3c4699fde82')

[XT SQL Error]