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', 'qea6ju1c491f6mh3gok3sdivf7', '216.73.217.152', '1791148702', '1791148702', '/products_new.php?XTCsid=adfc0e11230ba3fd4e1b3e35346ba1dc')

[XT SQL Error]