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', '60ro1kh0s6m0iudlu6kpvm7eo4', '216.73.216.28', '1765006701', '1765006701', '/index.php?XTCsid=7c604026da355cfd6a094c68b431572d&cat=c12_Music.html')

[XT SQL Error]