//Silme fonksiyonunu yazalım :
 public void Delete(ForeignMembers foreignMembers)
 {
     using (InstituteDbEntities context = new InstituteDbEntities())
     {
         var entity = context.Entry(foreignMembers);
         entity.State = EntityState.Deleted;
         context.SaveChanges();
     }
 }
        //Ekleme fonksiyonunu yazalım :
        public void Add(ForeignMembers foreignMembers)
        {
            using (InstituteDbEntities context = new InstituteDbEntities())
            {
                //context.ForeignMembers.Add(foreignMembers);
                //context.SaveChanges();

                var entity = context.Entry(foreignMembers);
                entity.State = EntityState.Added;
                context.SaveChanges();
            }
        }