Displaying set of images based on time

[Qjay]

Hello , i have a set of images that are locally stored in system and have a database which looks something like this

When the user opens the app , it should read the system time and get the image based on which is closest to current time .

currently i am doing something like this , don't know if it's right way but if you guys have better more optimized way please suggest. Below is the code

QString return_diff(QHash<QString, QString> mantra)
{
    QTime sys_time;
    QHash<QString, QTime>result;
        sys_time =  QTime::currentTime();
    QHashIterator<QString, QString> i(mantra);
    while(i.hasNext())
    {
        QString server_timeID = i.key();
        QString server_time = i.value();
        QStringList splitted_time = server_time.split(":");

        QString hrs = splitted_time.at(0);
        QString min = splitted_time.at(1);
        int int_hrs =hrs.toInt();
        int int_min = min.toInt();
        QTime notify_time(int_hrs,int_min,0,0);
        if(notify_time >= sys_time)
        {
            result.insert(server_timeID,notify_time);
        }

    }
    QString image;
    QHashIterator<QString, QTime> j(result);
    QTime min(0,0,0,0);
    while(j.hasNext())
    {
        if(j.value() < min)
        {
            image = j.key();
        }
    }


    return image;


}

QString dbmanager::getImage_url()
{
    QString db_path = QStandardPaths::writableLocation(QStandardPaths::GenericDataLocation);
    QString email = "";

    qDebug() << db_path;
    QDir dir(db_path);
    dir.cd("MANTRA_appdata");

    QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");//not dbConnection
       db.setDatabaseName(dir.absoluteFilePath("MANTRA.db"));
       if(!db.open())
       {
           qDebug() <<"error in opening DB";
       }
       else
       {
           qDebug() <<"connected to DB" ;

       }
       QSqlQuery query;
       QString image;

       query.prepare("SELECT email from User where ID = 1");


       if(query.exec() && (query.size() > 0 || query.size() != -1))
       {
          qDebug() << "done";
          email = query.value(0).toString();
          QHash<QString, QString> mantra;
          query.prepare("SELECT mantra_type time FROM Mantra WHERE enabled = true AND email = '" + email + "'");
          while(query.next())
          {
              mantra.insert(query.value(0).toString(),query.value(0).toString());
          }

          image = return_diff(mantra);

       }
       else
       {
           image = "Mantra1.png";
       }
       image = dir.absolutePath() + "/" + image;


       return image;

}