protected function modify(Category $category)
 {
     $q = $this->dao->prepare('UPDATE ' . $this->table() . ' SET NAME = :name, DESCRIPTION = :description, PARENT_CATEGORY_ID = :parentCategoryId, IS_ROOT = :isRoot WHERE ID = :id');
     $q->bindValue(':name', $category->getName());
     $q->bindValue(':description', $category->getDescription());
     $q->bindValue(':parentCategoryId', $category->getParentCategoryId());
     $q->bindValue(':isRoot', $category->getIsRoot());
     $q->bindValue(':id', $category->id(), PDO::PARAM_INT);
     $q->execute();
 }