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', 'fsdc3ueqds2ubnr667qtv22pt3', '216.73.216.180', '1766699504', '1766699504', '/shop_content.php?XTCsid=a63f52844b6e675f480eaf86612536c2&coID=3')

[XT SQL Error]