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', '5dcobocrssq6r0anod5lhgq7b4', '216.73.217.0', '1790162499', '1790162499', '/index.php?XTCsid=64790e0110a034a2b6e4fd66b54409ef')

[XT SQL Error]