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', 't4icu5f4t6thb0p1namgggib12', '216.73.216.9', '1758119824', '1758119824', '/index.php?XTCsid=e0aff158e2bf6f9b0e0972d20fcb54b7')

[XT SQL Error]