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', 'a0561m5c24mago2u94skhojbq6', '216.73.216.121', '1761864214', '1761864214', '/index.php?XTCsid=620b4786e082478ad6dd00018e954119&cat=c12_Music.html&language=en')

[XT SQL Error]