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', 'ibbj6m0c7g047nj07phgj4a140', '216.73.217.172', '1790517719', '1790517719', '/products_new.php?XTCsid=4299a8bbf7f56cb5a06703b866244eb3')

[XT SQL Error]