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', 'vhha5cj3tokhpd9f588kgfgg74', '216.73.216.139', '1770454794', '1770454794', '/index.php?XTCsid=d8fb38e8fa3ae8ffd83e3fe617bdce5f')

[XT SQL Error]