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', 'eu7vtmv8q988b83k5o81rd0bu5', '216.73.216.63', '1773849135', '1773849135', '/products_new.php?XTCsid=d163dd0fc0b54bf3066f85422c77e00a')

[XT SQL Error]