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', 'ad706f01bc853168a4075d45a26e6c2b', '216.73.217.75', '1789292210', '1789292210', '/shop/index.php?cat=c2_.html')

[XT SQL Error]