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', 'bvt1sk7ktcrq7h1e0ir1333uf7', '216.73.216.9', '1758147243', '1758147243', '/shop_content.php?XTCsid=cdfc0f2ea8be6cebe1f6056b0a37d83f&coID=1')

[XT SQL Error]