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', '3ibdvkclaid3blh8gfb5esgb63', '216.73.216.80', '1751319535', '1751319535', '/index.php?XTCsid=a502d5cfc6fa87ac2ae3dc3ad36bf0da')

[XT SQL Error]