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', 'k0db1mvulvc442927jhirj5k25', '216.73.216.167', '1762554808', '1762554808', '/index.php?XTCsid=e65207aee44f142683bacdd3544c84a8&cat=c5_Crockery.html')

[XT SQL Error]