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    Qt World Summit: Early-Bird Tickets

    Selecting data from mysql using qt?

    General and Desktop
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    • D
      Dii last edited by

      ok, you have wrong apostrof type there. I mean this >> '

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      • D
        doforumda last edited by

        i tried without apostrophes as well but same error

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        • D
          Dii last edited by

          nope, you had ` before the root and not '
          that was the error

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          • D
            Dii last edited by

            ok, wait a second, I checked it in the meantime and it won't work without password, stay tuned, I post the right command

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            • D
              doforumda last edited by

              you mean like this
              grant all on testTwo.* to root@localhost ;
              if yes it also displaying same error

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              • D
                Dii last edited by

                so, here we go:

                grant all on testTwo.* to 'root'@'localhost' identified by 'password';

                Make the right apostrophes! :) You have to set the password in your Qt app too.

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                • D
                  Dii last edited by

                  ok, wait I see

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                  • D
                    Dii last edited by

                    the Devnet's forum motor changes the apostrophes somehow... use the straight apostrophes everywhere
                    I mean this @'@

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                    • D
                      doforumda last edited by

                      mysql query did its job its now successful but when i use qt code and try to make it run it displays same error

                      @
                      Starting /home/zafar/c++/dbExample-build-desktop/dbExample...
                      false
                      QSqlQuery::exec: database not open
                      /home/zafar/c++/dbExample-build-desktop/dbExample exited with code 0
                      @

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                      • D
                        doforumda last edited by

                        wait i think the query is not sucessful because it displays this message 0 rows affected
                        @
                        mysql> grant all on testTwo.* to 'root'at'localhost' identified by 'password';
                        Query OK, 0 rows affected (0.01 sec)
                        @

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                        • L
                          lyuts last edited by

                          Add this to your code after connecting:

                          @qDebug() << db.lastError().text();@

                          And tell us what the error is.

                          I'm a rebel in the S.D.G.

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                          • L
                            lyuts last edited by

                            [quote author="doforumda" date="1286877766"]wait i think the query is not sucessful because it displays this message 0 rows affected
                            @
                            mysql> grant all on testTwo.* to 'root'at'localhost' identified by 'password';
                            Query OK, 0 rows affected (0.01 sec)
                            @[/quote]

                            Did you run that command with 'password' instead of '123456'?

                            I'm a rebel in the S.D.G.

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                            • D
                              Dii last edited by

                              0 rows is just fine with the grant command... have you set the password on

                              @db.setPassword("password");@

                              ?

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                              • D
                                doforumda last edited by

                                this is the output after adding lastError.text()
                                @
                                Starting /home/zafar/c++/dbExample-build-desktop/dbExample...
                                " "
                                false
                                QSqlQuery::exec: database not open
                                /home/zafar/c++/dbExample-build-desktop/dbExample exited with code 0
                                @

                                lyut: yes i use command with 'password' not '123456'

                                Dii sorry i didnt understand this db.setPassword("password");
                                where should i set this

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                                • L
                                  lyuts last edited by

                                  [quote author="doforumda" date="1286878193"]
                                  lyut: yes i use command with 'password' not '123456'

                                  Dii sorry i didnt understand this db.setPassword("password");
                                  where should i set this[/quote]

                                  1. I assume you should have specified the actual password when running that query.
                                  2. @db.setPassword("password");@ should be added to your source code just where you set db options.

                                  I'm a rebel in the S.D.G.

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                                  • D
                                    doforumda last edited by

                                    i ran query again with actual password
                                    i have already setup password in my qt code here it is
                                    @
                                    #include <QApplication>
                                    #include <QtSql>

                                    int main(int argc, char *argv[])
                                    {
                                    QCoreApplication a(argc, argv);

                                    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
                                    db.setDatabaseName("testTwo");
                                    db.setUserName("root");
                                    db.setPassword("123456");
                                    db.setHostName("localhost");
                                    
                                    qDebug() << db.lastError().text();
                                    
                                    bool ok = db.open();
                                    qDebug() << ok;
                                    
                                    QSqlQuery query;
                                    query.exec&#40;"SELECT firstname,lastname FROM testTable"&#41;;
                                    while(query.next()) {
                                        QString firstName = query.value(0).toString();
                                        QString secondName = query.value(1).toString();
                                        qDebug() << "First Name: " << firstName << "Last Name:" << secondName;
                                        qDebug() << db.lastError();
                                    }
                                    return 0;
                                    

                                    }

                                    @

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                                    • D
                                      Dii last edited by

                                      db.lasterror().text() should come after line 16 (db.open()).
                                      The password in the Qt code must be the same what you have specified in the GRANT command above.

                                      I suspect probably, you haven't made the database and the table in mysql yet, if you go back to mysql command line, what do you get by these commands:

                                      @SHOW databases;

                                      USE testTwo;

                                      SHOW tables;@

                                      I go to dinner, be back in a few minutes :)

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                                      • L
                                        lyuts last edited by

                                        You put my debug before opening the connection. Put it after.

                                        I'm a rebel in the S.D.G.

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                                        • D
                                          doforumda last edited by

                                          i changed db.lastError().text(); and place it after db.open()
                                          this is the output
                                          @
                                          Starting /home/zafar/c++/dbExample-build-desktop/dbExample...
                                          "Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) QMYSQL: Unable to connect"
                                          false
                                          QSqlQuery::exec: database not open
                                          /home/zafar/c++/dbExample-build-desktop/dbExample exited with code 0
                                          @

                                          the commands in mysql displayed are here
                                          repectively to your commands

                                          @
                                          mysql> show databases;
                                          +--------------------+
                                          | Database |
                                          +--------------------+
                                          | information_schema |
                                          | cdcol |
                                          | mysql |
                                          | phpmyadmin |
                                          | test |
                                          | testTwo |
                                          +--------------------+
                                          6 rows in set (0.01 sec)

                                          mysql> use testTwo
                                          Database changed
                                          mysql> show tables
                                          -> ;
                                          +-------------------+
                                          | Tables_in_testTwo |
                                          +-------------------+
                                          | testTable |
                                          +-------------------+
                                          1 row in set (0.01 sec)

                                          @

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                                          • D
                                            doforumda last edited by

                                            any clues?

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