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', 'fb94mn4l4v0jjnhj0mrsr35j90', '3.85.92.139', '1561472854', '1561472854', '/popup_content.php/coID/1')

[XT SQL Error]