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', '0osrtjclu85m0qihs1ngq26bp3', '216.73.216.121', '1761809963', '1761809963', '/index.php?XTCsid=0045c82a20eb26c176bef1fc0ba16df3&cat=c5_Crockery.html&language=en')

[XT SQL Error]