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', '7ghvhv7o7t0e603v1691pgqps3', '216.73.217.151', '1788641102', '1788641102', '/product_info.php?XTCsid=1455d70b156c4853db961f68b595bbe7&info=p21_Paper-tablecloth-10-meters.html')

[XT SQL Error]