public Administrador AtualizarAdministrador(Administrador administrador)
 {
     using (MyCompanyContext db = new MyCompanyContext())
     {
         db.Entry(administrador).State = System.Data.Entity.EntityState.Modified;
         db.SaveChanges();
         return administrador;
     }
 }
 public Aluno AtualizarAluno(Aluno aluno)
 {
     using (MyCompanyContext db = new MyCompanyContext())
     {
         db.Entry(aluno).State = System.Data.Entity.EntityState.Modified;
         db.SaveChanges();
         return aluno;
     }
 }
 public Empresa AtualizarEmpresa(Empresa empresa)
 {
     using (MyCompanyContext db = new MyCompanyContext())
     {
         db.Entry(empresa).State = System.Data.Entity.EntityState.Modified;
         db.SaveChanges();
         return empresa;
     }
 }