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', 'gg0cjglduuevtr6oc6mm3bpgm0', '216.73.217.147', '1777934814', '1777934814', '/index.php?XTCsid=1edacbd1b1da241cee49f7b785c52673')

[XT SQL Error]