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Connect to MYSQL failed in Qt

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qt6c++mysqlmysql server
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  • S SGaist
    7 May 2021, 11:14

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

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    ELEMENTICY
    wrote on 7 May 2021, 11:16 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

    S 1 Reply Last reply 7 May 2021, 18:43
    0
    • S SGaist
      7 May 2021, 11:14

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

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      ELEMENTICY
      wrote on 7 May 2021, 11:17 last edited by
      #20

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

      S 1 Reply Last reply 7 May 2021, 18:44
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      • E ELEMENTICY
        7 May 2021, 11:16

        @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

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        SGaist
        Lifetime Qt Champion
        wrote on 7 May 2021, 18:43 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.

        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 ELEMENTICY
          7 May 2021, 11:17

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

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          SGaist
          Lifetime Qt Champion
          wrote on 7 May 2021, 18:44 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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            ELEMENTICY
            wrote on 8 May 2021, 05:07 last edited by ELEMENTICY 5 Aug 2021, 05:08
            #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...

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              ELEMENTICY
              wrote on 8 May 2021, 05:18 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

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                SGaist
                Lifetime Qt Champion
                wrote on 8 May 2021, 06:38 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 8 May 2021, 10:14
                1
                • S SGaist
                  8 May 2021, 06:38

                  "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 ?

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                  ELEMENTICY
                  wrote on 8 May 2021, 10:14 last edited by ELEMENTICY 5 Aug 2021, 10:15
                  #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 8 May 2021, 10:20
                  0
                  • E ELEMENTICY
                    8 May 2021, 10:14

                    @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
                    
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                    ELEMENTICY
                    wrote on 8 May 2021, 10:20 last edited by
                    #27

                    @ELEMENTICY im sure i entered correct server info

                    J 1 Reply Last reply 8 May 2021, 10:59
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                    • E ELEMENTICY
                      8 May 2021, 10:20

                      @ELEMENTICY im sure i entered correct server info

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                      JonB
                      wrote on 8 May 2021, 10:59 last edited by JonB 5 Aug 2021, 10:59
                      #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 8 May 2021, 13:08
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                      • S Offline
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                        SGaist
                        Lifetime Qt Champion
                        wrote on 8 May 2021, 11:22 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

                        E 1 Reply Last reply 8 May 2021, 13:08
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                        • S SGaist
                          8 May 2021, 11:22

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

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                          ELEMENTICY
                          wrote on 8 May 2021, 13:08 last edited by
                          #30

                          @SGaist yes there is

                          S 1 Reply Last reply 8 May 2021, 18:52
                          0
                          • J JonB
                            8 May 2021, 10:59

                            @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?

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                            ELEMENTICY
                            wrote on 8 May 2021, 13:08 last edited by
                            #31

                            @JonB no password,only root

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                            • E ELEMENTICY
                              8 May 2021, 13:08

                              @SGaist yes there is

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                              SGaist
                              Lifetime Qt Champion
                              wrote on 8 May 2021, 18:52 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 9 May 2021, 09:33
                              1
                              • S SGaist
                                8 May 2021, 18:52

                                @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.

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                                ELEMENTICY
                                wrote on 9 May 2021, 09:33 last edited by
                                #33

                                @SGaist ok lemme try,if i understand what documentation say lol

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