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', '0rsp57o9ms5fk6uf06dphvreh1', '54.166.186.79', '1493443207', '1493443207', '/')

[XT SQL Error]