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', 'psopbf4rsp3e51ftt4lghfv6i3', '216.73.216.52', '1774884337', '1774884337', '/xtshop/password_double_opt.php')

[XT SQL Error]