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', 'lmjg0avt0vudttrhq31bani437', '216.73.216.9', '1757976853', '1757976853', '/index.php?XTCsid=ec34e8689ca02683c909010c614b53e3')

[XT SQL Error]