One to Many LINQ Query - compiler error

Question

Please see the LINQ query below:

var test = from s in db.Students
           join c in db.Courses on s.courseid equals c.id into d
           where s.name.StartsWith("Bert")
           select new Student { id=s.id,name=s.name, Course = d.Select(x => x.name) };

A student links to one courses. Therefore the value of Course in the above should be a collection of courses. However, there is a compiler error (System.ArguementNullException). What am I doing wrong?

I am competent using SQL, however I am new to LINQ. Please see the SQL from the database below:

***Student Class***
  public partial class Student
    {
        public int id { get; set; }
        public string name { get; set; }
        public Nullable<int> age { get; set; }
        public Nullable<int> courseid { get; set; }

        public virtual Course Course { get; set; }
    }

    Course Class

 public partial class Course
    {
        public Course()
        {
            this.Students = new HashSet<Student>();
        }

        public int id { get; set; }
        public string name { get; set; }

        public virtual ICollection<Student> Students { get; set; }
    }

Answer 1

It seems you are just trying to get your query to also retrieve the Course navigation property for your students. As such, all you need to do is Include it:

var students = db.Students
    .Include(s => s.Course)
    .Where(s => s.Name.StartsWith("Bert");