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', 'c0jertstq9lpaf68d08scdgr31', '216.73.216.130', '1760975018', '1760975018', '/popup_content.php?XTCsid=cdfc0f2ea8be6cebe1f6056b0a37d83f&coID=1')

[XT SQL Error]