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', 'e30tsidpcouvrtq0ifk1c7p313', '216.73.216.80', '1751314902', '1751314902', '/index.php?cat=c6_Foodstuffs.html&XTCsid=7c604026da355cfd6a094c68b431572d')

[XT SQL Error]