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', '28jo30fuspdngeolhhp8tul6d2', '216.73.216.76', '1789027424', '1789027424', '/index.php?XTCsid=9eb59f02daaaa8febdf279447bcbfdb4')

[XT SQL Error]