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', '5d5p9n2s7hhs6hfi1l8ijpvoj0', '216.73.216.180', '1766142981', '1766142981', '/index.php?XTCsid=67a1ee4a966bad4e2954e4e321814afb&cat=c12_Music.html')

[XT SQL Error]