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Connect to MYSQL failed in Qt

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qt6c++mysqlmysql server
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  • S Offline
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    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 Online
        C Online
        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

        1 Reply Last reply
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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
            E Offline
            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
              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
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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

                1 Reply Last reply
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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
                  S Offline
                  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

                  1 Reply Last reply
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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
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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 ?

                          E Offline
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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

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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
                                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

                                    1 Reply Last reply
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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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