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', '6fkackr661dqa1mhe3j869u7s5', '216.73.216.110', '1752046786', '1752046786', '/index.php?cat=c6_Foodstuffs.html&XTCsid=0045c82a20eb26c176bef1fc0ba16df3')

[XT SQL Error]