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', '1d039507cf920bee86dbdf9e28921d8b', '216.73.217.165', '1780980819', '1780980819', '/shop/product_info.php?info=p85_.html')

[XT SQL Error]