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', '4a9v1dj54s630vniit830gduj1', '216.73.216.9', '1758160113', '1758160113', '/index.php?XTCsid=38f09672db884903e3803adf9d076819&cat=c8_Disposable-tableware.html')

[XT SQL Error]