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', 'a178ukl32m4o2cpliclj283ve2', '216.73.216.9', '1758176582', '1758176582', '/product_info.php?XTCsid=cdfc0f2ea8be6cebe1f6056b0a37d83f&info=p18_Fun-Hat.html')

[XT SQL Error]