How do I write something like this:
int result = database .Where(x => x.Name == "Criteria") .Sum(x => x.Count)) ?? 0;
Where it will return the sum value unless linq does not find anything in which case it will return 0.
EDIT: The field is not null-able.
EDIT 2: I am using Entity Framework.
You were very close with your original query. You only needed to cast your
int result = database .Where(x => x.Name == "Criteria") .Sum(x => (int?)x.Count) ?? 0;
Doing it this way would be a little more efficient and elegant than wrapping it in a Try/Catch.
I suspect you are using Entity Framework. If you were just using Linq-to-Objects, the solutions everybody else have provided would have worked.