Qt接続mysqlクエリーデータ

QSqlDatabase db=QSqlDatabase::addDatabase("QMYSQL");
       db.setHostName("127.0.0.1");//mysql   
       db.setPort(3306);
       db.setDatabaseName("thinkcmf");//        
       db.setUserName("root");//mysql   
       db.setPassword("xxx");//mysql  
       if(db.open())
       {
           qDebug()<<"success!";
            qDebug()<"show tables from thinkcmf");//thinkcmf        
            while (query.next()) {
                QString country = query.value(0).toString();
                qDebug()<"select * from thinkcmf_menu");//      
            while (query1.next()) {
                QString country = query1.value(0).toString();//cmf_menu  1      
                qDebug()<else{
           qDebug()<<"failure";
       }