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', 'oasch8mlau2n26rdu3scuu9940', '216.73.216.80', '1751325559', '1751325559', '/shop_content.php?language=en&coID=2&XTCsid=69a1e06b1d537d651878c63fe4ee3fec')

[XT SQL Error]