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', '6dnn8o1ep8qe3qkibd1s9e36t4', '216.73.216.113', '1775566267', '1775566267', '/index.php?XTCsid=81fba26e1f006e30d12d9ee4d58a4030&cat=c4_Beer-Mugs.html')

[XT SQL Error]