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', 'kn1fiej4ct5q6rr9n22fr797m1', '216.73.216.147', '1751762506', '1751762506', '/product_info.php?info=p14_65-drinking-cups-1-2-Liter.html&XTCsid=7c604026da355cfd6a094c68b431572d')

[XT SQL Error]