Skip to content
  • Categories
  • Recent
  • Tags
  • Popular
  • Users
  • Groups
  • Search
  • Get Qt Extensions
  • Unsolved
Collapse
Brand Logo
  1. Home
  2. Qt Development
  3. General and Desktop
  4. Selecting data from mysql using qt?
Forum Updated to NodeBB v4.3 + New Features

Selecting data from mysql using qt?

Scheduled Pinned Locked Moved General and Desktop
150 Posts 7 Posters 150.0k Views 1 Watching
  • Oldest to Newest
  • Newest to Oldest
  • Most Votes
Reply
  • Reply as topic
Log in to reply
This topic has been deleted. Only users with topic management privileges can see it.
  • D Offline
    D Offline
    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...

    1 Reply Last reply
    0
    • L Offline
      L Offline
      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.

      1 Reply Last reply
      0
      • D Offline
        D Offline
        Dii
        wrote on last edited by
        #61

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

        1 Reply Last reply
        0
        • D Offline
          D Offline
          doforumda
          wrote on last edited by
          #62

          i tried without apostrophes as well but same error

          1 Reply Last reply
          0
          • D Offline
            D Offline
            Dii
            wrote on last edited by
            #63

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

            1 Reply Last reply
            0
            • D Offline
              D Offline
              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

              1 Reply Last reply
              0
              • D Offline
                D Offline
                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

                1 Reply Last reply
                0
                • D Offline
                  D Offline
                  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.

                  1 Reply Last reply
                  0
                  • D Offline
                    D Offline
                    Dii
                    wrote on last edited by
                    #67

                    ok, wait I see

                    1 Reply Last reply
                    0
                    • D Offline
                      D Offline
                      Dii
                      wrote on last edited by
                      #68

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

                      1 Reply Last reply
                      0
                      • D Offline
                        D Offline
                        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
                        @

                        1 Reply Last reply
                        0
                        • D Offline
                          D Offline
                          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)
                          @

                          1 Reply Last reply
                          0
                          • L Offline
                            L Offline
                            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.

                            1 Reply Last reply
                            0
                            • L Offline
                              L Offline
                              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.

                              1 Reply Last reply
                              0
                              • D Offline
                                D Offline
                                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");@

                                ?

                                1 Reply Last reply
                                0
                                • D Offline
                                  D Offline
                                  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

                                  1 Reply Last reply
                                  0
                                  • L Offline
                                    L Offline
                                    lyuts
                                    wrote on 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.

                                    1 Reply Last reply
                                    0
                                    • D Offline
                                      D Offline
                                      doforumda
                                      wrote on 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;
                                      

                                      }

                                      @

                                      1 Reply Last reply
                                      0
                                      • D Offline
                                        D Offline
                                        Dii
                                        wrote on 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 :)

                                        1 Reply Last reply
                                        0
                                        • L Offline
                                          L Offline
                                          lyuts
                                          wrote on last edited by
                                          #78

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

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

                                          1 Reply Last reply
                                          0

                                          • Login

                                          • Login or register to search.
                                          • First post
                                            Last post
                                          0
                                          • Categories
                                          • Recent
                                          • Tags
                                          • Popular
                                          • Users
                                          • Groups
                                          • Search
                                          • Get Qt Extensions
                                          • Unsolved