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', 'c9qp0fhv22bpmqjf2paqhumdq7', '216.73.216.118', '1761490516', '1761490516', '/index.php?XTCsid=e786190734d0d1381d87ecc8370dc449&cat=c9_Tischdekoration.html')

[XT SQL Error]