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Selecting data from mysql using qt?

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  • T Offline
    T Offline
    tony
    wrote on last edited by
    #10

    Did you leave

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

    commented?

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    0
    • D Offline
      D Offline
      doforumda
      wrote on last edited by
      #11

      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 Offline
        D Offline
        doforumda
        wrote on last edited by
        #12

        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 Offline
          D Offline
          Dmytro
          wrote on last edited by
          #13

          Try uncomment line 23

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          0
          • D Offline
            D Offline
            doforumda
            wrote on last edited by
            #14

            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 Offline
              D Offline
              Dmytro
              wrote on last edited by
              #15

              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 Offline
                D Offline
                doforumda
                wrote on last edited by
                #16

                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 Offline
                  D Offline
                  doforumda
                  wrote on last edited by
                  #17

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

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                  • D Offline
                    D Offline
                    Dmytro
                    wrote on last edited by
                    #18

                    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 Offline
                      D Offline
                      doforumda
                      wrote on last edited by
                      #19

                      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 Offline
                        D Offline
                        Dmytro
                        wrote on last edited by
                        #20

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

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                        • D Offline
                          D Offline
                          doforumda
                          wrote on last edited by
                          #21

                          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 Offline
                            D Offline
                            doforumda
                            wrote on last edited by
                            #22

                            anyone who can help?

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                            • D Offline
                              D Offline
                              Dmytro
                              wrote on last edited by
                              #23

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

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                              • D Offline
                                D Offline
                                doforumda
                                wrote on last edited by
                                #24

                                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 Offline
                                  D Offline
                                  Dii
                                  wrote on last edited by
                                  #25

                                  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 Offline
                                    D Offline
                                    doforumda
                                    wrote on last edited by
                                    #26

                                    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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                                    • L Offline
                                      L Offline
                                      lyuts
                                      wrote on last edited by
                                      #27

                                      Are you able to connect to your DB from shell?

                                      I'm a rebel in the S.D.G.

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                                      • D Offline
                                        D Offline
                                        doforumda
                                        wrote on last edited by
                                        #28

                                        i dont know how to connect to my DB from shell. I install xampp which is easy for me to manage my databases.
                                        how can i connect from shell?

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                                        • L Offline
                                          L Offline
                                          lyuts
                                          wrote on last edited by
                                          #29

                                          @mysql -h host -D dbname -u user@

                                          I guess your can omit host parameter if you are connecting to localhost. You might need to specify "-p password" switch also (depends on mysql configuration).

                                          I'm a rebel in the S.D.G.

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