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', 'pg3r9n2alu1j9dce9e3uvpfbf4', '216.73.216.69', '1789730840', '1789730840', '/index.php?XTCsid=7da72f1737c0cce1944c3631fc48aa29')

[XT SQL Error]