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  4. QSqlDatabasePrivate::removeDatabase

QSqlDatabasePrivate::removeDatabase

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  • N Offline
    N Offline
    Niak74
    wrote on last edited by
    #10

    Got it, but where do you call MysqlConnector2::close() (outside this class).

    Does the error message appear when you close your app, or when you call MysqlConnector2::close() method ? (verify this point using debug mode and breakpoints !)

    I recommand you to make atomic methods that implie to open AND close connection to your DB. By this way, you will be sure release your resources.

    See the EDIT in my previous message.

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    • R Offline
      R Offline
      rileo8
      wrote on last edited by
      #11

      Here i call the close():

      @ conn->close();
      logger->close();
      logger->logOnFile("MainButton","mousePressEvent","Exiting from program.");
      exit(0);
      @

      just before exiting...

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      • L Offline
        L Offline
        luca
        wrote on last edited by
        #12

        I do this:
        @
        db->close();
        delete db;
        QSqlDatabase::removeDatabase(dbName);
        @

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        • R Offline
          R Offline
          rileo8
          wrote on last edited by
          #13

          Thanks for the suggestion!

          Doing like this it works:

          @bool MysqlConnector2::close()
          {
          bool result=true;

          QString connection;
          connection=db.connectionName();
          db.close();
          delete &db;
          QSqlDatabase::removeDatabase(connection);
          
          
          return result;
          

          }@

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          • T Offline
            T Offline
            tobias.hunger
            wrote on last edited by
            #14

            delete &db is really aehm... ugly! You are calling the destructor on a stack-allocated object. This will lead to the destructor of db getting called twice, once when you do it and once when it goes out of scope. Undefined behaviour is lurking here... nothing I want close to my databases;-)

            You could hold a pointer to a db instead, initializing it like this db = new QSqlDatabase(QSqlDatabase::addDatabase(...));

            That pointer can be deleted properly in your close method.

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            • R Offline
              R Offline
              rileo8
              wrote on last edited by
              #15

              You are right,

              that was only an attempt.

              Now i will modify the code to be less ugly..eheheh

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              • C Offline
                C Offline
                chikymanzanares
                wrote on last edited by
                #16

                finally, how do you solve the problem?

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                • S Offline
                  S Offline
                  SaiyanRiku
                  wrote on last edited by
                  #17

                  Nice, it works for me too, just by declaring a pointer instead of an object and using it like this:

                  @
                  m_db = new QSqlDatabase(QSqlDatabase::addDatabase("QSQLITE"));
                  m_szConnectionName = m_db->connectionName();
                  ...
                  m_db->open();
                  ...
                  m_db->close();
                  ...
                  delete m_db
                  QSqlDatabase::removeDatabase(m_szConnectionName);
                  @

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                  • S Offline
                    S Offline
                    SherifOmran
                    wrote on last edited by
                    #18

                    how do you define m_db?

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                    0
                    • S Offline
                      S Offline
                      SherifOmran
                      wrote on last edited by
                      #19

                      ok i found it
                      QSqlDatabase *db;

                      thanks it worked for me

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