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', 'a11a6480b037c3b97c198afae62eab9c', '216.73.217.75', '1789292182', '1789292182', '/shop/index.php?cPath=3')

[XT SQL Error]