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', 'ri9pq5f0qr645oiv08j6cp5254', '54.196.107.247', '1495571377', '1495571377', '/shop_content.php?coID=3')

[XT SQL Error]