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', '12od5ojccfi0g77pr7afc73uq4', '54.196.107.247', '1495571426', '1495571426', '/popup_content.php?coID=1')

[XT SQL Error]