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', '21sd7gk8hlnm1bbnhppakj4kc0', '216.73.216.7', '1758243511', '1758243511', '/products_new.php?XTCsid=1ce6d0a6925740e42ccf6986944a240a')

[XT SQL Error]