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', '6adhuptcjv748alt9mu512do26', '216.73.217.68', '1789303832', '1789303832', '/index.php?XTCsid=98aceda5b74686030567a1049a2325c8')

[XT SQL Error]