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', 'ff6d83ee71e7ae555f32d868215d5fa0', '216.73.217.165', '1780980884', '1780980884', '/shop/product_info.php?info=p37_.html')

[XT SQL Error]