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', 'hvm8gbncq0p5b8n00tgebuj1p3', '54.224.255.158', '1498515435', '1498515435', '/product_info.php?info=p638_Suppenschuessel--Dino-s-Ursuppe-.html&refID=nlrss')

[XT SQL Error]