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', '6o3em3cj6eiurpm763pbpci584', '216.73.216.118', '1761652989', '1761652989', '/shop_content.php?XTCsid=5452c15f57f0ea9ce022f9dc9cfaa045&coID=4')

[XT SQL Error]