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', 'tfm3rkn5bls2p53rcqa3qarqp0', '216.73.216.9', '1758164183', '1758164183', '/index.php?XTCsid=1da9cb6c210c3c669470161f7aeedf2d')

[XT SQL Error]