Question

I have an Entity Class called Session and it containts two attributes: LecturerOne and LectureTwo. I want to create a union of all the distinct names in LecturerOne and LecturerTwo:

I got just LecturerOne working.

public List<string> ListLecturer()
{
    var lecturerNames = (from s in db.Sessions                
                         select s.LecturerOne).Distinct();

    List<string> lecturerList = lecturerNames.ToList(); 
    return lecturerList;
}

Answer 1

One option:

var list = db.Sessions.SelectMany(s => new string[] { s.LecturerOne,
                                                      s.LecturerTwo })
                      .Distinct()
                      .ToList();

I don’t know offhand how EF will treat that, but it’s worth a try…

Alternatively, similar to Jamiec’s answer but IMO simpler:

var list = db.Sessions.Select(s => s.LecturerOne)
                      .Union(db.Sessions.Select(s => s.LecturerTwo))
                      .ToList();

(Union already returns distinct results, so there’s no need to do it explicitly.)