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', 'e3ur5nsfrph0gmsotc6b2u0k61', '216.73.216.87', '1765605703', '1765605703', '/index.php?XTCsid=69b3fcc0fb5a34f08b494675bac7e6ec')

[XT SQL Error]