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', 'gcvef2em80jo3si8dgm1s55nh1', '216.73.216.251', '1781860788', '1781860788', '/index.php?XTCsid=adc8c520bddaa9e02a40df1e2a90f128&cat=c13_Accessoires.html')

[XT SQL Error]