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', '66i25t2bdn99vpn1oi7oo4o8m0', '216.73.216.70', '1752611201', '1752611201', '/index.php?cat=c12_Music.html&XTCsid=d0fb6f95a363340d124d7dc76e615e44')

[XT SQL Error]