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', '689ht1gct019lmejn22e9746e7', '216.73.216.165', '1752392776', '1752392776', '/product_info.php?info=p21_Paper-tablecloth-10-meters.html&XTCsid=a0c8d0b3d08cb472c84559a313755d47')

[XT SQL Error]