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', 'c0f2cc477a1fa2aeb2b81711e566f56f', '216.73.216.42', '1763384106', '1763384106', '/shop/index.php?cat=c26_.html')

[XT SQL Error]