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', 'jp7rqcmpsvd2a8ok10ljc9qgn5', '216.73.216.9', '1757991052', '1757991052', '/index.php?XTCsid=744c226086359bc1d698caea9179572f')

[XT SQL Error]