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', 'u31bsuctht845nnm9bpks69m16', '216.73.216.165', '1752394182', '1752394182', '/index.php?cat=c5_Crockery.html&XTCsid=e65207aee44f142683bacdd3544c84a8')

[XT SQL Error]