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Selecting data from mysql using qt?

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  • D Offline
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    doforumda
    wrote on last edited by
    #55

    whats the reason that my database is not opening in qt?

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      Dii
      wrote on last edited by
      #56

      lyuts: yes \q is working too

      doforumda: ok, so get into the mysql comand line with the command above

      /opt/lampp/bin/mysql -D testTwo -h localhost -u root -p

      and then do this:

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

      Then we have a working mysql, and the rights are granted, we can get back to your Qt program.

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      • L Offline
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        lyuts
        wrote on last edited by
        #57

        I hope the next post will be like "Hooray, I got it working!!!" :)

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

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          doforumda
          wrote on last edited by
          #58

          there is an error in sql syntax
          @
          mysql> grant all on testTwo.* to ‘root’@’localhost’;
          ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '��root’@’localhost’' at line 1
          @

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          • D Offline
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            Dii
            wrote on last edited by
            #59

            Ok, back to your Qt program:

            @#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("");
            db.setHostName("localhost");
            
            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;
            

            }@

            Notice, we don't set a password here.
            The end is 'return 0' instead of 'a.exec()', and it won't hang. The exec() starts the main event loop, and you don't use it here...

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              lyuts
              wrote on last edited by
              #60

              I think you need to check apostrophes in that command.

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

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                Dii
                wrote on last edited by
                #61

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

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                  doforumda
                  wrote on last edited by
                  #62

                  i tried without apostrophes as well but same error

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                    Dii
                    wrote on 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 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 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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                          Dii
                          wrote on 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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                            Dii
                            wrote on last edited by
                            #67

                            ok, wait I see

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                              Dii
                              wrote on 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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                                doforumda
                                wrote on 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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                                  doforumda
                                  wrote on 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
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                                    lyuts
                                    wrote on 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 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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                                        Dii
                                        wrote on 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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                                          doforumda
                                          wrote on 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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