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', '9isto3j22bkifrir9f4rk2ain4', '216.73.217.78', '1789823229', '1789823229', '/index.php?XTCsid=a8f768c639dfd62c2d6d3cd7ed21b720&cat=c5_Crockery.html')

[XT SQL Error]