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', '7pg52f3t86fak1eqbq4eu9n6g1', '216.73.216.7', '1758233314', '1758233314', '/index.php?XTCsid=49fc75412bccc50f2ce0a3b1ee60899a')

[XT SQL Error]