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', 'klco0crbr97c4p3v9lb9l5i2k2', '216.73.216.176', '1762313725', '1762313725', '/index.php?XTCsid=cf4692a620e8efffd6d37fae4c1bd5ad')

[XT SQL Error]