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, http_referer) values ('', 'Guest', 'dl62mpjmjhrvcvlea7qa8771c6', '172.17.0.19', '1454980132', '1454980132', '/shop/index.php?cat=c4_Tickets.html', '')

[XT SQL Error]