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', 'mhhgqpo6k7q2hqsfl76m42c7i0', '216.73.216.9', '1758215846', '1758215846', '/shop_content.php?XTCsid=ca28ab8f46bb6e791b42fe9b92719761&coID=1')

[XT SQL Error]