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', '419rm7rccnu1ilcro23umj3p86', '216.73.217.120', '1787779235', '1787779235', '/xtshop/index.php?cat=c106_.html')

[XT SQL Error]