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', '4i8dha0nd6n0jul058q8oi56m5', '216.73.216.172', '1767751112', '1767751112', '/shop_content.php?XTCsid=7c604026da355cfd6a094c68b431572d&coID=3')

[XT SQL Error]