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', 'ngfaft66uofgd499i2j0i8voq0', '216.73.216.60', '1760482190', '1760482190', '/index.php?XTCsid=c60d173e05a16d5feea88bc4b1883fc9')

[XT SQL Error]