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', 'oubh7olgl3mdagvcim3kqsf513', '216.73.216.244', '1752210331', '1752210331', '/index.php?cat=c8_Disposable-tableware.html&XTCsid=a6fef95dcbdcf765a3c6baf6e1fe0e25')

[XT SQL Error]