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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, 11:03

    @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.

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    ELEMENTICY
    wrote on 7 May 2021, 11:05 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
    

    ?

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    • S Offline
      S Offline
      SGaist
      Lifetime Qt Champion
      wrote on 7 May 2021, 11:08 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

      E 1 Reply Last reply 7 May 2021, 11:12
      1
      • S SGaist
        7 May 2021, 11:08

        No space no "lib" prefix.

        It's explained in the documentation

        E Offline
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        ELEMENTICY
        wrote on 7 May 2021, 11:12 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

        S 1 Reply Last reply 7 May 2021, 11:14
        0
        • E ELEMENTICY
          7 May 2021, 05:52

          @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
          
          C Offline
          C Offline
          Christian Ehrlicher
          Lifetime Qt Champion
          wrote on 7 May 2021, 11:13 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

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          • E ELEMENTICY
            7 May 2021, 11:12

            @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

            S Offline
            S Offline
            SGaist
            Lifetime Qt Champion
            wrote on 7 May 2021, 11:14 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 7 May 2021, 11:16
            0
            • S SGaist
              7 May 2021, 11:14

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

              E Offline
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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.

                E Offline
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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
                0
                • 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

                  S Offline
                  S Offline
                  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

                    S Offline
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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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                    • E Offline
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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...

                      1 Reply Last reply
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                      • E Offline
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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

                        1 Reply Last reply
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                        • S Offline
                          S Offline
                          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
                              0
                              • E ELEMENTICY
                                8 May 2021, 10:20

                                @ELEMENTICY im sure i entered correct server info

                                J Online
                                J Online
                                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
                                  S Offline
                                  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
                                  0
                                  • 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?

                                      E Offline
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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.

                                          E Offline
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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

                                          1 Reply Last reply
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