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', 'd2c98j3atq5leanj64qsr0kri4', '216.73.216.80', '1751324089', '1751324089', '/index.php?cat=c6_Foodstuffs.html&XTCsid=fee111602053381265bc5ad0a64c84d2')

[XT SQL Error]