public static ArrayList<Subcategorias> sqlSelectTodos(){
        ArrayList<Subcategorias> subcat = new ArrayList();
        if(!BD.getInstance().sqlSelect("SELECT * FROM subcategorias ORDER BY idsubcategorias DESC")){
            return subcat;
        }        
        while(BD.getInstance().sqlFetch()){
            subcat.add(new Subcategorias(BD.getInstance().getInt("id")
                                        ,BD.getInstance().getString("nombre") ));
        }
        return subcat;
    }