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', 'ai9uvs1jag3sji40osi2ldvq87', '216.73.216.87', '1765623204', '1765623204', '/products_new.php?XTCsid=274ec9b60c94b159bd8f2b261ed48387')

[XT SQL Error]