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', 'o1aier3gtam5su5hnld51n1d23', '216.73.217.80', '1790182168', '1790182168', '/index.php?XTCsid=792dd2eece839333bab562194e3fb545&cat=c13_Accessoires.html')

[XT SQL Error]