private void detach_students(student entity)
		{
			this.SendPropertyChanging();
			entity.dept1 = null;
		}
		private void attach_students(student entity)
		{
			this.SendPropertyChanging();
			entity.dept1 = this;
		}
 partial void Updatestudent(student instance);
 partial void Deletestudent(student instance);
 partial void Insertstudent(student instance);