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', 'k8qsven3gphrf7jf83k4r9h494', '216.73.216.113', '1752883959', '1752883959', '/shop_content.php?coID=4&XTCsid=ca28ab8f46bb6e791b42fe9b92719761')

[XT SQL Error]