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', 'aa2a84frqj0vackn5jfndhds23', '216.73.216.9', '1758163149', '1758163149', '/index.php?XTCsid=e786190734d0d1381d87ecc8370dc449&cat=c9_Tischdekoration.html')

[XT SQL Error]