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Can't open a mysql-db on pi

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  • MichlM Offline
    MichlM Offline
    Michl
    wrote on last edited by
    #1

    I'm trying to open and access a mysql-db on a pi. I've built a cross development environment and it works fine.
    The problem now is this snippet:

    dbAbholer.addDatabase("QMYSQL");
    dbAbholer.setHostName("localhost");
    dbAbholer.setDatabaseName("test");
    dbAbholer.setUserName("user");
    dbAbholer.setPassword("password");
    bool ret = dbAbholer.open();
    qDebug() << ret;
    qDebug() << "---------------------------";
    qDebug() << dbAbholer.lastError().text();
    qDebug() << "---------------------------";
    qDebug() << qApp->libraryPaths();
    qDebug() << QSqlDatabase::drivers();

    The output is:

    Unable to query physical screen size, defaulting to 100 dpi.
    To override, set QT_QPA_EGLFS_PHYSICAL_WIDTH and QT_QPA_EGLFS_PHYSICAL_HEIGHT (in millimeters).
    false

    "Driver not loaded Driver not loaded"

    ("/usr/local/Qt-5.5.1-raspberry/plugins", "/home/pi")
    ("QSQLITE", "QSQLITE2", "QMYSQL", "QMYSQL3", "QTDS", "QTDS7")

    The access to the db should work, i've tried it via mysql-command line.

    Whats wrong with my code?

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    • MichlM Offline
      MichlM Offline
      Michl
      wrote on last edited by
      #2

      I tried a lot of things and find out the solution:

      False:
      QSqlDatabase dbAbholer;
      dbAbholer.addDatabase("QMYSQL");

      Right:
      QSqlDatabase dbAbholer = QSqlDatabase::addDatabase("QMYSQL");

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      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #3

        Hi and welcome to devnet,

        addDatabase is a static method that's why it didn't work. However, didn't you got a compiler warning when doing that ?

        Interested in AI ? www.idiap.ch
        Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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        • MichlM Offline
          MichlM Offline
          Michl
          wrote on last edited by
          #4

          Thanks for your response. No i did not recognize any error while compiling.
          Well my development environment is: Windows PC with a virtual machine running ubuntu. The target is a raspberry. So its a cross-environment. Perhaps this is the reason?
          BTW, it tooks a very long time to build this environment with all drivers for sql, touch etc. Especially the touch in combination with eglfs was very hard (one need tslib from other sources etc.)

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          • SGaistS Offline
            SGaistS Offline
            SGaist
            Lifetime Qt Champion
            wrote on last edited by
            #5

            Not an error, a warning.

            Embedded development is rarely a piece of cake ;)

            Interested in AI ? www.idiap.ch
            Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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