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', '1nr9eappbb5gs6obfs3hnc0772', '216.73.216.197', '1751518102', '1751518102', '/index.php?cat=c8_Disposable-tableware.html&XTCsid=72205775904d1a5c41b590dd7b5ff1d6')

[XT SQL Error]