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Selecting data from mysql using qt?

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  • D Offline
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    Dii
    wrote on 12 Oct 2010, 09:46 last edited by
    #61

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

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    • D Offline
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      doforumda
      wrote on 12 Oct 2010, 09:48 last edited by
      #62

      i tried without apostrophes as well but same error

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      • D Offline
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        Dii
        wrote on 12 Oct 2010, 09:49 last edited by
        #63

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

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        • D Offline
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          Dii
          wrote on 12 Oct 2010, 09:51 last edited by
          #64

          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 Offline
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            doforumda
            wrote on 12 Oct 2010, 09:51 last edited by
            #65

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

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            • D Offline
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              Dii
              wrote on 12 Oct 2010, 09:52 last edited by
              #66

              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 Offline
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                Dii
                wrote on 12 Oct 2010, 09:52 last edited by
                #67

                ok, wait I see

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                • D Offline
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                  Dii
                  wrote on 12 Oct 2010, 09:53 last edited by
                  #68

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

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                  • D Offline
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                    doforumda
                    wrote on 12 Oct 2010, 10:01 last edited by
                    #69

                    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 Offline
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                      doforumda
                      wrote on 12 Oct 2010, 10:02 last edited by
                      #70

                      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 Offline
                        L Offline
                        lyuts
                        wrote on 12 Oct 2010, 10:03 last edited by
                        #71

                        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 Offline
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                          lyuts
                          wrote on 12 Oct 2010, 10:04 last edited by
                          #72

                          [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 Offline
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                            Dii
                            wrote on 12 Oct 2010, 10:05 last edited by
                            #73

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

                            @db.setPassword("password");@

                            ?

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                            • D Offline
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                              doforumda
                              wrote on 12 Oct 2010, 10:09 last edited by
                              #74

                              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 Offline
                                L Offline
                                lyuts
                                wrote on 12 Oct 2010, 10:13 last edited by
                                #75

                                [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 Offline
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                                  doforumda
                                  wrote on 12 Oct 2010, 10:15 last edited by
                                  #76

                                  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 Offline
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                                    Dii
                                    wrote on 12 Oct 2010, 10:18 last edited by
                                    #77

                                    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 Offline
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                                      lyuts
                                      wrote on 12 Oct 2010, 10:21 last edited by
                                      #78

                                      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 Offline
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                                        doforumda
                                        wrote on 12 Oct 2010, 10:24 last edited by
                                        #79

                                        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 Offline
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                                          doforumda
                                          wrote on 12 Oct 2010, 10:38 last edited by
                                          #80

                                          any clues?

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