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', '5raco75qg872uldeap1043af02', '216.73.216.80', '1751318748', '1751318748', '/index.php?XTCsid=97ccfe04b51dc1a45e1177cb04737958')

[XT SQL Error]