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', 'oc5749gn7hsus16stbcq6kju82', '216.73.216.9', '1758219368', '1758219368', '/shop_content.php?XTCsid=33509f1bee4ee2cbb673a74e5faae0d4&coID=1')

[XT SQL Error]