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', 'ee4kfm2l4akls95ukaflgfjr60', '216.73.216.63', '1774480539', '1774480539', '/index.php?XTCsid=56bc3ceb4448b083b620d4a52c6c076d')

[XT SQL Error]