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', '4vv216osos98h7b2ee9dnl4332', '216.73.216.9', '1758029392', '1758029392', '/index.php?XTCsid=3ff39c1ecd10603727f45351a658e742')

[XT SQL Error]