/**
  * Método para actualizar el registro
  */
 public static void update(users user)
 {
     using (var conn = new db_entities()) {
         try {
             var entity = conn.users.Where(x => x.id == user.id).FirstOrDefault();
             user.updated_at = new DateTime();
             if (entity == null)
             {
                 throw new NotExistsException();
             }
             else
             {
                 if (user.password == null || user.password == "")
                 {
                     conn.SP_USER_UPDATE_WITHOUT_PASSWORD(user.id, user.name, user.email, user.rol_id, user.unit_id,
                                                          DateTime.Now, user.state);
                 }
                 else
                 {
                     conn.SP_USER_UPDATE_WITH_PASSWORD(user.id, user.name, user.email, user.password, user.rol_id, user.unit_id,
                                                       DateTime.Now, user.state);
                 }
             }
         } catch (Exception e) {
             throw e;
         }
     }
 }