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', '352nj6adlkqmk9h6rdfs01q3n1', '216.73.216.165', '1752394370', '1752394370', '/index.php?XTCsid=744c226086359bc1d698caea9179572f')

[XT SQL Error]