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', '0585kip3cr7hlnopir0baubtc3', '216.73.217.147', '1778012138', '1778012138', '/index.php?XTCsid=e545d49a9ebb1bd8a4abf38803b4309a')

[XT SQL Error]