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', 'at305egthp86k1lm1jm3r5mjc5', '216.73.216.139', '1770495319', '1770495319', '/index.php?XTCsid=e07b29ea8ec62b3899f39e64b0b0774c')

[XT SQL Error]