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', '0u7rkubi6u93u4pp0sqh3v0315', '216.73.216.197', '1751520446', '1751520446', '/index.php?XTCsid=4635a65037080db684b109117d2fc14c')

[XT SQL Error]