private void Submit()
        {
            // Student.JoiningDate = string.Empty;

            Students.Add(Student);
            Student = new Student();
        }
 public ViewModel()
 {
     Student = new Student();
     Students = new ObservableCollection<Student>();
     Students.CollectionChanged += new System.Collections.Specialized.NotifyCollectionChangedEventHandler(Students_CollectionChanged);
 }