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', 'seimtbc20pikt81mu0nrr5cp32', '216.73.216.19', '1763070452', '1763070452', '/index.php?XTCsid=620b4786e082478ad6dd00018e954119&cat=c12_Music.html&language=en')

[XT SQL Error]