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', 'o97uq86comnbli8ph32lkijg55', '216.73.216.121', '1761863680', '1761863680', '/index.php?XTCsid=159458ffcd70853368c82c29206c1527&cat=c13_Accessoires.html')

[XT SQL Error]