Mapping computed properties in Linq-to-SQL to actuall SQL statements

var activeContracts = customer.Contracts.Where(w => w.ContractEndDate == null);

var activeContracts = customer.ActiveContracts;

var singleContractCustomers = db.Customers.Where(w => w.ActiveContracts.Count() == 1);

public static Expression<Func<Customer, bool>> HasActiveContract
    {
        get { return cust => cust.Contracts.Count() == 1; }
    }

var filtered = db.Customers.Where(Customer.HasActiveContract);

public IQueryable<Customer> CustomersWithActiveContract
    {
        get { return Customers.Where(Customer.HasActiveContract); }
    }

{SELECT [t0].[CustomerID], [t0].[cFirstName], [t0].[cLastName]
FROM [dbo].[Customers] AS [t0]
WHERE ((
    SELECT COUNT(*)
     FROM [dbo].[Contracts] AS [t1]
    WHERE (([t1].[ContractEndDate] > @p0) OR ([t1].[ContractEndDate] IS NULL)) AND ([t1].[cId] = [t0].[cId])
    )) > @p1
}