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', 'j7fv3rp0atvh5veottu5jmu1o1', '216.73.217.68', '1789351031', '1789351031', '/products_new.php?XTCsid=6c2468ca28c6c182aaed37353d32ae32')

[XT SQL Error]