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', '9b6hhj3t1mara2onip5qt8rft5', '216.73.216.110', '1752049486', '1752049486', '/index.php?cat=c2_Decoration.html&XTCsid=69a1e06b1d537d651878c63fe4ee3fec')

[XT SQL Error]