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', 'sn9h1o2peoui0ho3u65mhumfl4', '216.73.216.180', '1767023302', '1767023302', '/')

[XT SQL Error]