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', '3afvjrffee599b46qmcsh6av20', '216.73.216.121', '1761842906', '1761842906', '/index.php?XTCsid=1ce6d0a6925740e42ccf6986944a240a&cat=c8_Disposable-tableware.html')

[XT SQL Error]