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', 'du5o01kohttg2s2o43cglkucc2', '216.73.216.197', '1751512754', '1751512754', '/product_info.php?info=p8_100-Placemats.html&XTCsid=7c604026da355cfd6a094c68b431572d')

[XT SQL Error]