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', '84ee3c30b80286cb1c8082f66a81e73d', '216.73.216.132', '1759471327', '1759471327', '/shop/index.php?cat=c29_.html')

[XT SQL Error]