为啥数据库输出的时候只有一条。数据库里面有好几条数据

为什么数据库输出的时候只有一条。数据库里面有好几条数据
 QSqlDatabase dbconndb;
       // for(int i=0;i<3;i++)
     dbconndb =QSqlDatabase::database("first");//获得db1.
     QSqlQuery query12(dbconndb);
     int dbCount=0;
    while(!dbconn.open())    {
    }
    
    query12.exec("select * from install");

     while(query12.next())   {
                       // querycount++;
         QString ele0;QString ele1;QString ele2;QString ele3;QString ele4;QString ele5;QString ele6;
         QString ele7;QString ele8;

                     ele0=query12.value(0).toString();//query.value(0)是id的值，将其转换为int型
                     ele1=query12.value(1).toString();
                     ele2=query12.value(2).toString();
                     ele3=query12.value(3).toString();
                     ele4=query12.value(4).toString();
                     ele5=query12.value(5).toString();
                     ele6=query12.value(6).toString();
                     ele7=query12.value(7).toString();
                     ele8=query12.value(8).toString();

                    qDebug()<<ele0<<ele1<<ele2<<ele3<<ele4<<ele5<<ele6<<ele7<<ele8;//输出两个值
                     //if(ele8=="0"){
                     query12.prepare("UPDATE install SET upId=:a where upId='0'");
                      query12.bindValue(":a","1");

                                 tableString tableBuff;
                                 tableBuff.ele0=ele0;
                                    tableBuff.ele1=ele1;