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', 'gpnsu7jgk9o80oe6iqe6keoiu6', '216.73.217.153', '1781554521', '1781554521', '/index.php?XTCsid=1a719986c059fb57d0cc5ade098128f1')

[XT SQL Error]