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', 'os4piist69ourdibapub0eo9f3', '216.73.216.244', '1752211563', '1752211563', '/index.php?XTCsid=f54d8739844de79bbca5fee789c5b9c7')

[XT SQL Error]