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', '76mftshhmuso55mquu23v0cb46', '216.73.217.68', '1789313593', '1789313593', '/index.php?XTCsid=ffc7b7ad1b3e91bdeba4a0a7be929bdd')

[XT SQL Error]