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', 'l20cv6k8q9s6e0sdquaj4halb7', '216.73.216.63', '1773815317', '1773815317', '/index.php?XTCsid=d3095b02705efe527622b406f0082775')

[XT SQL Error]