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', 'l12eddu380hcv4g4857kb9biq5', '216.73.216.60', '1760727006', '1760727006', '/popup_content.php?XTCsid=1ce6d0a6925740e42ccf6986944a240a&coID=1')

[XT SQL Error]