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    Selecting data from mysql using qt?

    General and Desktop
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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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                                      • D
                                        doforumda last edited by

                                        well i dont have that option. here is what i get
                                        when i click file/new file or project then this screenshot
                                        "Your text to link here...":http://www.freeimagehosting.net/uploads/702f633ae7.png
                                        then i keep clicking next getting the follwoing screenshots
                                        "Your text to link here...":http://www.freeimagehosting.net/uploads/ab872acfb8.png
                                        "Your text to link here...":http://www.freeimagehosting.net/uploads/45c51ab364.png
                                        "Your text to link here...":http://www.freeimagehosting.net/uploads/84605eae46.png
                                        "Your text to link here...":http://www.freeimagehosting.net/uploads/84605eae46.png

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                                        • D
                                          Dii last edited by

                                          Well, it should make no problem to have SQL query before exec(), at least I don't have any problem with that.

                                          Let's get back to square one:
                                          You said if you uncomment the
                                          @bool ok = db.open();@
                                          then your program hangs. Can we see the value of 'ok'?
                                          @qDebug() << ok;@
                                          My guess is probably you have problems granting the rights in mysql when you've created the table... have you made
                                          @GRANT ALL ON testTwo.* to 'root'at'localhost' IDENTIFIED BY 'somepassword';@
                                          (Ouch please replace the 'at' with the 'at' sign, the forum motor uses it for code tags, I don't know how to write it... I hope it's not confusing.
                                          I'm not sure if you can do it with empty password, I guess yes, but I never do that.)

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                                          • D
                                            doforumda last edited by

                                            i now put password for root at localhost.
                                            when i place qDebug() << ok then it displays this
                                            @
                                            false
                                            QSqlQuery::exec: database not open
                                            @

                                            false might be the value of ok.

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