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', 'avphe0cnledn67bnm8rs45pi97', '216.73.216.16', '1758226673', '1758226673', '/popup_content.php?XTCsid=ec23ca965190a8290c666be9c9947acd&coID=1')

[XT SQL Error]