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', 'seiknr35p11likcq591q4vema2', '216.73.216.197', '1751520783', '1751520783', '/index.php?cat=c2_Decoration.html&XTCsid=85f438a686cbfb5e3ea5e5d6b9611958')

[XT SQL Error]