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', 'aqbc888tr6vqt2qjas6l5kpus0', '216.73.216.9', '1758040785', '1758040785', '/index.php?XTCsid=2b50d004ceffb62515815b0230b19dd4&cat=c4_Beer-Mugs.html')

[XT SQL Error]