向数据库添加新记录时出现问题，错误：QSqlQuery::value：未定位在有效记录上

如何解决向数据库添加新记录时出现问题，错误：QSqlQuery::value：未定位在有效记录上

我认为我的问题是::QSqlQuery::value: 未定位在有效记录上。 我使用 Pgadmin。我使用 Pgadmin 将新表和对象、记录添加到我的数据库中。

我无法在我的数据库中添加一个新点但我可以完美地删除（删除）一个。

我有带点的界面。我可以通过简单地选择一个点并使用删除选项来删除它。我也添加了点选项，但它没有添加到数据库中。

我无法确定我的问题，所以我将不胜感激！

QSqlDatabase Database::getDb() const
{
    return db;
}

Database::Database(QObject *parent) : QObject(parent)
{
    db = QSqlDatabase::addDatabase("QPSQL");
    db.setHostName(settings.dbpath.get());
    db.setDatabaseName("main");
    db.setUserName("postgres");
    db.setPort(5432);
    db.setPassword("root");
    if(!db.open()){
        auto problemDialog = new InfoDialog(InfoDialog::Warning,"Baza danych","Aplikacja napotkała na problem z połączeniem z bazą danych",nullptr,true);
        problemDialog->show();
        qDebug()<<"There is a problem with database.";
        return;
    }
    QSqlQuery query;
    query.exec("truncate active_errors");
}

void Database::addError(Error* error) {
    if(error==nullptr) return;
    QSqlQuery query;
    query.exec("INSERT INTO active_errors (source,value,hint,noticable,noticed,log,showinbar,clicked) VALUES ('"
                +error->source+"','"
                +error->value+"','"
                +error->hint+"',"
                +QVariant(error->noticable).toString()+","
                +QVariant(error->noticed).toString()+","
                +QVariant(error->log).toString()+","
                +QVariant(error->showInBar).toString()+","
                +QVariant(error->clicked).toString()+
                ") RETURNING id;"
                );
    if(query.next())
        error->setDbId(query.value(0).toInt());

}
void Database::updateSingleValueIn(const QString& dbName,const QString& valName,const QString& value,int id) {
    QSqlQuery query;
    query.exec("""UPDATE """+dbName+""" SET """+valName+"""="""+value+""" WHERE id="""+QString::number(id)+""";""");
}

void Database::updateErrorClicked(Error *error)
{
    if(error->getDbId()<0) return;
    QSqlQuery query;
    query.exec("SELECT clicked FROM active_errors WHERE id="+QString::number(error->getDbId())+";");
    query.next();
    error->clicked = query.value(0).toBool();
}
void Database::removeMultipleErrorsByID(const QList<int> &ids)
{
    if(ids.count()<=0) return;
    QString toDelete="";
    for(auto id: ids) {
        toDelete+=QString::number(id)+",";
    }
    toDelete.chop(1);
    QSqlQuery query;
    query.exec("DELETE FROM active_errors WHERE id IN("+toDelete+");");
}

int Database::addIntegral(const QString& name,const QString& ip,const QString& km,qreal posx,qreal posy,int imgId,const QStringList& zones,const QString& pass)
{
    QSqlQuery query;
    QString zonesString = "";
    foreach(auto zone,zones) {
        zonesString+=zone+",";
    }
    zonesString.chop(1);
    query.exec("""INSERT INTO integrals (name,ip,km,posx,posy,image,zones,pass,malfunctions) VALUES ('"""+name+"""','"""+ip+"""','"""+km+"""','"""+QString::number(posx)+"""','"""+QString::number(posy)+"""','"""+QString::number(imgId)+"""','"""+zonesString+"""','"""+pass+"""','EMPTY,OUT1,OUT2,OUT3,OUT4,+KPD,+EX1/2,BATT,AC,DT1,DT2,DTM,RTC,no DTR,no BATT,ext. modem,ext. model') RETURNING id;""");
    query.next();
    return query.value(0).toInt();
}

void Database::updateIntegral(int id,const QString& name,";
    }
    zonesString.chop(1);
    query.exec("""UPDATE integrals SET name='"""+name+"""',km='"""+km+"""',ip='"""+ip+"""',image='"""+QString::number(imgId)+"""',zones='"""+zonesString+"""',pass='"""+pass+"""' WHERE id="""+QString::number(id)+""";""");
}

int Database::addInput(Inputs &input,int connectionID,const QPointF& pos)
{
    QSqlQuery query;
    query.exec("""INSERT INTO inputs (name,inputid,connectionid,type) VALUES ('"""+
                input.getName()+"""','"""+
                QString::number(input.getInputID())+"""','"""+
                QString::number(connectionID)+"""','"""+
                QString::number(pos.x())+"""','"""+
                QString::number(pos.y())+"""','"""+
                QString::number(static_cast<int>(input.getSensorType()))+"""') RETURNING id;""");
    query.next();
    return query.value(0).toInt();
}

void Database::removeIntegral(int id)
{
    QSqlQuery query;
    query.exec("""DELETE FROM integrals WHERE id="""+QString::number(id)+""";""");
    query.exec("DELETE FROM inputs WHERE connectionid="+QString::number(id)+";");
}

QSqlQueryModel* Database::getModelByName(const QString& name,int startsEndsWith) {
    auto toRet = new QSqlQueryModel();
    auto qry = QSqlQuery(db);
    if(startsEndsWith==0) {
        qry.prepare("""select * from integrals WHERE value='"""+name+"""';""");
    } else if(startsEndsWith==1) {

    } else if(startsEndsWith>=2) {

    }
    qry.exec();
    toRet->setQuery(qry);
    return toRet;
}

QSqlQueryModel *Database::getModel(const QString& text)
{
    QSqlQueryModel *toRet = new QSqlQueryModel();
    QSqlQuery* qry = new QSqlQuery(db);
    qry->prepare("""select * from integrals WHERE"""+text);
    qry->exec();
    toRet->setQuery(*qry);
    return toRet;
}

QSqlQueryModel *Database::getAllIntegrals()
{
    QSqlQueryModel *toRet = new QSqlQueryModel();
    QSqlQuery* qry = new QSqlQuery(db);
    qry->prepare("select * from integrals");
    qry->exec();
    toRet->setQuery(*qry);
    return toRet;
}

QSqlQueryModel *Database::getAllInputs(int id)
{
    QSqlQueryModel *toRet = new QSqlQueryModel();
    QSqlQuery* qry = new QSqlQuery(db);
    qry->prepare("select * from inputs WHERE connectionid="+QString::number(id)+";");
    qry->exec();
    toRet->setQuery(*qry);
    return toRet;
}

当我尝试添加新点时，出现错误消息：

QSqlQuery::value: not positioned on a valid record