public static boolean existsName(Clientes cli){
        String sql = " SELECT * FROM clientes WHERE rut = '"+cli.getRut()+"' AND dv = '"+cli.getDv()+"' ";        
        if(!BD.getInstance().sqlSelect(sql)){
            return false;
        }
        if(!BD.getInstance().sqlFetch()){
            return false;
        }
        return true;
    }