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', 'e1vu6dbrupnak9lg869blkgo00', '216.73.216.9', '1758177641', '1758177641', '/index.php?XTCsid=a62bc14a2472a2e20215fc39a8dcda1a')

[XT SQL Error]