Not sure that i have fully understood the question, becuase it will be difficult to count that which does not exist. If you want a list of records that does not exist in a referenced table, then you could look at a left join.
eg. In northwind to prove the customers that have not placed any orders you could:
select c.companyname,o.orderid
from customers c left join orders o on c.customerid = o.customerid
where o.orderid is null
..Should return two rows. Hope this helps.