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', 'tksblroeurt8ehr8iui8238803', '216.73.216.113', '1775359947', '1775359947', '/index.php?XTCsid=9aa3413fa4b87d7b3aaad07cc354d9e8')

[XT SQL Error]