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Connect to MYSQL failed in Qt

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qt6c++mysqlmysql server
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  • E ELEMENTICY

    @Christian-Ehrlicher

    This is for sure not correct.

    oh,how do i fix it?

    SGaistS Offline
    SGaistS Offline
    SGaist
    Lifetime Qt Champion
    wrote on last edited by
    #13

    @ELEMENTICY said in Connect to MYSQL failed in Qt:

    @Christian-Ehrlicher

    This is for sure not correct.

    oh,how do i fix it?

    Re-read my previous answer.

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

    E 1 Reply Last reply
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    • SGaistS SGaist

      @ELEMENTICY said in Connect to MYSQL failed in Qt:

      @Christian-Ehrlicher

      This is for sure not correct.

      oh,how do i fix it?

      Re-read my previous answer.

      E Offline
      E Offline
      ELEMENTICY
      wrote on last edited by
      #14

      @SGaist so i have to make it

      win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/ -l libmysql
      else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/ -l libmysqld
      else:unix: LIBS += -L$$PWD/lib/ -l libmysql
      

      ?

      1 Reply Last reply
      0
      • SGaistS Offline
        SGaistS Offline
        SGaist
        Lifetime Qt Champion
        wrote on last edited by
        #15

        No space no "lib" prefix.

        It's explained in the documentation

        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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        • SGaistS SGaist

          No space no "lib" prefix.

          It's explained in the documentation

          E Offline
          E Offline
          ELEMENTICY
          wrote on last edited by
          #16

          @SGaist my current profile code:

          win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/ -llibmysql
          else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/ -llibmysqld
          else:unix: LIBS += -L$$PWD/lib/ -llibmysql
          

          documentation:

          LIBS += -L"3rdparty/CatWhisperer/lib" -lCatWhisperer
          

          i got this error:
          :-1: error: error: cannot find -llibmysql

          proof that path exists:
          Screenshot 2021-05-07 191143.png

          SGaistS 1 Reply Last reply
          0
          • E ELEMENTICY

            @Christian-Ehrlicher i do,

            win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/libmysql
            else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/libmysqld
            else:unix: LIBS += -L$$PWD/lib/libmysql
            

            And yea,use qt sql it just give like 11 error
            And if i use official mysql mysql.h,it only give 2 error which is undefine

            And yea,or i need to change my profile's lib code to this?

            win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/libmysql.lib
            else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/libmysqld.lib
            else:unix: LIBS += -L$$PWD/lib/libmysql.lib
            
            Christian EhrlicherC Offline
            Christian EhrlicherC Offline
            Christian Ehrlicher
            Lifetime Qt Champion
            wrote on last edited by
            #17

            @ELEMENTICY said in Connect to MYSQL failed in Qt:

            And yea,use qt sql it just give like 11 error

            What does this mean?

            Qt Online Installer direct download: https://download.qt.io/official_releases/online_installers/
            Visit the Qt Academy at https://academy.qt.io/catalog

            1 Reply Last reply
            0
            • E ELEMENTICY

              @SGaist my current profile code:

              win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/ -llibmysql
              else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/ -llibmysqld
              else:unix: LIBS += -L$$PWD/lib/ -llibmysql
              

              documentation:

              LIBS += -L"3rdparty/CatWhisperer/lib" -lCatWhisperer
              

              i got this error:
              :-1: error: error: cannot find -llibmysql

              proof that path exists:
              Screenshot 2021-05-07 191143.png

              SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #18

              @ELEMENTICY did you read what I wrote ? No "lib" prefix.

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

              E 2 Replies Last reply
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              • SGaistS SGaist

                @ELEMENTICY did you read what I wrote ? No "lib" prefix.

                E Offline
                E Offline
                ELEMENTICY
                wrote on last edited by
                #19

                @SGaist
                current code:

                win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/libmysql
                else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/libmysqld
                else:unix: LIBS += -L$$PWD/lib/libmysql
                

                idk if i misunderstanded what u mean,but it still give error ;/
                or u mean i have to remove that -L

                SGaistS 1 Reply Last reply
                0
                • SGaistS SGaist

                  @ELEMENTICY did you read what I wrote ? No "lib" prefix.

                  E Offline
                  E Offline
                  ELEMENTICY
                  wrote on last edited by
                  #20

                  @SGaist and yea i dont know if its because im working on a android app,so it doesnt work

                  SGaistS 1 Reply Last reply
                  0
                  • E ELEMENTICY

                    @SGaist
                    current code:

                    win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/libmysql
                    else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/libmysqld
                    else:unix: LIBS += -L$$PWD/lib/libmysql
                    

                    idk if i misunderstanded what u mean,but it still give error ;/
                    or u mean i have to remove that -L

                    SGaistS Offline
                    SGaistS Offline
                    SGaist
                    Lifetime Qt Champion
                    wrote on last edited by
                    #21

                    @ELEMENTICY said in Connect to MYSQL failed in Qt:

                    @SGaist
                    current code:

                    win32:CONFIG(release, debug|release): LIBS += -L$$PWD/lib/libmysql
                    else:win32:CONFIG(debug, debug|release): LIBS += -L$$PWD/lib/libmysqld
                    else:unix: LIBS += -L$$PWD/lib/libmysql
                    

                    idk if i misunderstanded what u mean,but it still give error ;/
                    or u mean i have to remove that -L

                    You have to understand what -L and -l each do. I have already explained that before. So please re-read the corresponding answers.

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                    Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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                    • E ELEMENTICY

                      @SGaist and yea i dont know if its because im working on a android app,so it doesnt work

                      SGaistS Offline
                      SGaistS Offline
                      SGaist
                      Lifetime Qt Champion
                      wrote on last edited by
                      #22

                      @ELEMENTICY said in Connect to MYSQL failed in Qt:

                      @SGaist and yea i dont know if its because im working on a android app,so it doesnt work

                      Oracle does not provide pre-built binaries for Android.

                      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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                      • E Offline
                        E Offline
                        ELEMENTICY
                        wrote on last edited by ELEMENTICY
                        #23

                        @SGaist dude,im so tired...
                        Can you pleaseee write the 3 lines of code for me?
                        Please... i hope after you see this message,you wont just ignore and think i never hard work on it..But im tired for just add a simple library already...
                        It will be the BEST help for me

                        My current code...

                        win32:CONFIG(release, debug|release): LIBS += $$PWD/lib/ -llibmysql
                        else:win32:CONFIG(debug, debug|release): LIBS += $$PWD/lib/ -llibmysqld
                        else:unix: LIBS += $$PWD/lib/ -llibmysql
                        

                        Error:
                        :-1: error: error: cannot open C:/Users/ELEMENT/Documents/PosSystem/Pos/lib/: Permission denied
                        I opened QT Creator with Administrator,still same...

                        I also tried..

                        win32:CONFIG(release, debug|release): LIBS += $$PWD/lib/libmysql
                        else:win32:CONFIG(debug, debug|release): LIBS += $$PWD/lib/libmysqld
                        else:unix: LIBS += $$PWD/lib/libmysql
                        

                        Error:
                        :-1: error: no such file or directory: 'C:/Users/ELEMENT/Documents/PosSystem/Pos/lib/libmysql' clang++: error: no such file or directory: 'C:/Users/ELEMENT/Documents/PosSystem/Pos/lib/libmysql' make: *** [Makefile:79: libPos_x86_64.so] Error 1
                        Seems like that one is the wrong way to do without adding -l

                        appreciate it...

                        1 Reply Last reply
                        0
                        • E Offline
                          E Offline
                          ELEMENTICY
                          wrote on last edited by
                          #24

                          @SGaist I removed:

                          win32:CONFIG(release, debug|release): LIBS += $$PWD/lib/ -llibmysql
                          else:win32:CONFIG(debug, debug|release): LIBS += $$PWD/lib/ -llibmysqld
                          else:unix: LIBS += $$PWD/lib/ -llibmysql
                          

                          And tried only

                          LIBS += -L"lib" -llibmysql
                          

                          Still error:
                          :-1: error: error: cannot find -llibmysql

                          1 Reply Last reply
                          0
                          • SGaistS Offline
                            SGaistS Offline
                            SGaist
                            Lifetime Qt Champion
                            wrote on last edited by
                            #25

                            "Drop the lib prefix": -lmysql

                            To repeat myself: Oracle does not provide pre-built binaries for Android.

                            Also, @Christian-Ehrlicher already asked you several times: what exact error did you get with the QtSql module ?

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

                            E 1 Reply Last reply
                            1
                            • SGaistS SGaist

                              "Drop the lib prefix": -lmysql

                              To repeat myself: Oracle does not provide pre-built binaries for Android.

                              Also, @Christian-Ehrlicher already asked you several times: what exact error did you get with the QtSql module ?

                              E Offline
                              E Offline
                              ELEMENTICY
                              wrote on last edited by ELEMENTICY
                              #26

                              @SGaist ok its weird,it now dont give any error.But its EXCELENT!
                              But it unable to connect to Server
                              My code:

                              QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
                                      db.setHostName("localhost");
                                      db.setDatabaseName("pos");
                                      db.setUserName("root");
                              
                                      if (!db.open()){
                                          ui->error->setText("Oops,Unable to connect to Server!Please contact your Administrator for help.");
                                      }
                              

                              Includes:

                              #include <QtSql/QSql>
                              #include <QtSql/QSqlDatabase>
                              #include <QtSql/QSqlDriver>
                              #include <QtSql/QSqlQuery>
                              

                              and i also added sql to Qt in Profile

                              QT       += core gui sql
                              
                              E 1 Reply Last reply
                              0
                              • E ELEMENTICY

                                @SGaist ok its weird,it now dont give any error.But its EXCELENT!
                                But it unable to connect to Server
                                My code:

                                QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
                                        db.setHostName("localhost");
                                        db.setDatabaseName("pos");
                                        db.setUserName("root");
                                
                                        if (!db.open()){
                                            ui->error->setText("Oops,Unable to connect to Server!Please contact your Administrator for help.");
                                        }
                                

                                Includes:

                                #include <QtSql/QSql>
                                #include <QtSql/QSqlDatabase>
                                #include <QtSql/QSqlDriver>
                                #include <QtSql/QSqlQuery>
                                

                                and i also added sql to Qt in Profile

                                QT       += core gui sql
                                
                                E Offline
                                E Offline
                                ELEMENTICY
                                wrote on last edited by
                                #27

                                @ELEMENTICY im sure i entered correct server info

                                JonBJ 1 Reply Last reply
                                0
                                • E ELEMENTICY

                                  @ELEMENTICY im sure i entered correct server info

                                  JonBJ Offline
                                  JonBJ Offline
                                  JonB
                                  wrote on last edited by JonB
                                  #28

                                  @ELEMENTICY
                                  So your root user has no password to connect to MySQL?

                                  If db.open() fails, why don't you print out db.lastError() into your error message?

                                  E 1 Reply Last reply
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                                  • SGaistS Offline
                                    SGaistS Offline
                                    SGaist
                                    Lifetime Qt Champion
                                    wrote on last edited by
                                    #29

                                    Do you have a run time warning stating that the plugin cannot be loaded ?

                                    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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                                    • SGaistS SGaist

                                      Do you have a run time warning stating that the plugin cannot be loaded ?

                                      E Offline
                                      E Offline
                                      ELEMENTICY
                                      wrote on last edited by
                                      #30

                                      @SGaist yes there is

                                      SGaistS 1 Reply Last reply
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                                      • JonBJ JonB

                                        @ELEMENTICY
                                        So your root user has no password to connect to MySQL?

                                        If db.open() fails, why don't you print out db.lastError() into your error message?

                                        E Offline
                                        E Offline
                                        ELEMENTICY
                                        wrote on last edited by
                                        #31

                                        @JonB no password,only root

                                        1 Reply Last reply
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                                        • E ELEMENTICY

                                          @SGaist yes there is

                                          SGaistS Offline
                                          SGaistS Offline
                                          SGaist
                                          Lifetime Qt Champion
                                          wrote on last edited by
                                          #32

                                          @ELEMENTICY said in Connect to MYSQL failed in Qt:

                                          @SGaist yes there is

                                          Then build the plugin following the instructions from the
                                          documentation.

                                          As I already noted: there's no prebuilt Oracle MySQL library for Androïd. You will have to build the MariaDB libraries and then the plugin for that platform.

                                          As a side note: if you intend for your application to access that database through internet, you should reconsider that. It's a really bad idea to put a database in front of internet.

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

                                          E 1 Reply Last reply
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