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', 'efqgtjmfcbr6sr34p62n8pj6a3', '216.73.216.80', '1751317399', '1751317399', '/index.php?XTCsid=49fc75412bccc50f2ce0a3b1ee60899a')

[XT SQL Error]