Question

I’m doing LINQ to SQL, and when I add a group clause, it complains that my joining field does not exist. What am I missing?
I have:

var q = from f in db.Faults
        group f by f.FaultID into groupF
        join af in db.AvailabilityFaults on groupF.FaultID equals af.FaultID
        select groupF;

The problem is that it complains that ‘groupF.FaultID’ does not exist. If I remove the Group clause, then it works if I change the prefix alias (f.FaultID).

Answer 1

You need to join on the Group Key like so:

var q = from f in db.Faults
        group f by f.FaultID into groupF
        join af in db.AvailabilityFaults on groupF.Key equals af.FaultID
        select groupF

The Key value will be the FaultID for that group, so it should work as expected.