Max in linq to NHibernate for not exist data in database

Question

I have a query by linq to NHibernate.

var q = SessionInstance.Query<Request>().Max(e => e.Code);

If Request table has no rows, execution of this query raises GenericADOException with this message :

{"Could not execute query[SQL: SQL not available]"}

{"Value cannot be null.\r\nParameter name: item"}

What should I do?

Answer 1

Try this

SessionInstance.Query<Request>().Max(x => (int?)x.Code);

Answer 2

I think this should work with Linq-to-Nhibernate:

var q = SessionInstance.Query<Request>().Select(e => e.Code)
    .DefaultIfEmpty().Max();

or maybe DefaultIfEmpty(<some value>).