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', 'tn4a18g2ovrpu0of1st1pr2lk3', '216.73.216.80', '1751321214', '1751321214', '/index.php?cat=c5_Crockery.html&XTCsid=0045c82a20eb26c176bef1fc0ba16df3')

[XT SQL Error]