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', 'o7qiqo0s7usuds2vva8n44r0a0', '216.73.216.9', '1758017071', '1758017071', '/index.php?XTCsid=2b754bac84236c1c746619a0b6ab9e2d')

[XT SQL Error]