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', 'a5fh6f6r3ouchvaqqhn17c3sp3', '216.73.216.9', '1758198952', '1758198952', '/index.php?XTCsid=32b49b46b5da115de8e714f9609f9c5b')

[XT SQL Error]