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    Selecting data from mysql using qt?

    General and Desktop
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    • T
      tony last edited by

      Maybe an "#include <QVariant>" is missing at the top?

      T.

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      • M
        MTK358 last edited by

        Why not just

        @#include <QtCore>
        #include <QtSql>@

        and not worry about every single class you use?

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        • T
          tony last edited by

          That can be a solution only when you're testing something. So, in this case, I agree with you, let's avoid such worries.

          But if your project grows up, it's better to include what's needed, otherwise your compilation time can increase a lot.

          T.

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          • D
            doforumda last edited by

            i add #include <QVariant>

            now it is saying
            @
            QSqlQuery::exec: database not open
            @

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            • D
              Dmytro last edited by

              Try to use QSqlQuery::lastError() for find problem

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              • D
                doforumda last edited by

                what is the problem now in my code why it is not opening database?

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                • T
                  tony last edited by

                  Did you leave

                  @
                  //bool ok = db.open();
                  @

                  commented?

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                  • D
                    doforumda last edited by

                    well i changed my code to this and added lastError as well

                    @
                    #include <QApplication>
                    #include <QSqlDatabase>
                    #include <QSqlError>
                    #include <QSqlQuery>
                    #include <QDebug>
                    #include <QString>
                    #include <QVariant>
                    //#include <QtCore>
                    //#include <QtSql>
                    //#include "../connection.h"
                    #include "db.h"

                    int main(int argc, char *argv[])
                    {
                    QCoreApplication a(argc, argv);

                    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
                    db.setDatabaseName("testTwo");
                    db.setUserName("root");
                    db.setPassword("");
                    db.setHostName("localhost");
                    
                    //bool ok = db.open();
                    
                    QSqlQuery query;
                    query.exec&#40;"SELECT firstname,lastname FROM testTable"&#41;;
                    while(query.next()) {
                        QString firstName = query.value(0).toString();
                        QString secondName = query.value(1).toString();
                        qDebug() << "First Name: " << firstName << "Last Name:" << secondName;
                        qDebug() << db.lastError();
                    }
                    return a.exec&#40;&#41;;
                    

                    }
                    @

                    it still says QSqlQuery::exec: database not open

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                    • D
                      doforumda last edited by

                      it is still as commented
                      [quote author="Antonio Di Monaco" date="1286818410"]Did you leave

                      @
                      //bool ok = db.open();
                      @

                      commented?[/quote]

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                      • D
                        Dmytro last edited by

                        Try uncomment line 23

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                        • D
                          doforumda last edited by

                          i uncomment line 23 and comment everything below line 23 then it just says
                          @
                          Starting /home/zafar/c++/dbExample-build-desktop/dbExample...
                          @

                          and stucks there

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                          • D
                            Dmytro last edited by

                            OH! You use SQL code before
                            a.exec()
                            !
                            Are you sure?

                            Create standart QT GUI application and wrote sql code in mainwindow module.

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                            • D
                              doforumda last edited by

                              i am new to qt. how can i create Qt Gui App and do you mean i should write sql code in mainwindow.h file?

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                              • D
                                doforumda last edited by

                                right now i have three files. db.h, db,cpp and main.cpp

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                                • D
                                  Dmytro last edited by

                                  Run QT Creator.
                                  Use menu File/new file or project.
                                  Select QT Gui application.
                                  ...
                                  and select SQL checkbox
                                  ...
                                  and write sql code in MainWindow.cpp
                                  ...
                                  and see SQL Example please

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                                  • D
                                    doforumda last edited by

                                    well i tried "File/new file or project and select qt gui app" but i ddint find any sql checkbox anywhere in creating new project

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                                    • D
                                      Dmytro last edited by

                                      no coments...
                                      How can I send you screenshot?

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                                      • D
                                        doforumda last edited by

                                        you can add pictures here as screenshots or if you want my email address i ll give you that as well for screenshots

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                                        • D
                                          doforumda last edited by

                                          anyone who can help?

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                                          • D
                                            Dmytro last edited by

                                            !http://hin.dp.ua/files/down/qt_scr.PNG(my screenshot)!

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