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', 'rcik47e6a1nlahr9qotjkseq23', '216.73.216.84', '1764463489', '1764463489', '/xtshop/index.php?cat=c45_.html')

[XT SQL Error]