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 143.6k 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
    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
    @

    1 Reply Last reply
    0
    • 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

                                          • Login

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