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', 'pv6unh1p7j0i9a8q3rmqk9evj1', '216.73.216.144', '1781071065', '1781071065', '/xtshop/newsletter.php')

[XT SQL Error]