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', 'lbq3r8aajkhnl4vovd0i4l46m7', '216.73.216.9', '1758166677', '1758166677', '/index.php?XTCsid=a5ae7aa36aecd59295ef7c7c5e3b3701')

[XT SQL Error]