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    Call for Presentations - Qt World Summit

    Selecting data from mysql using qt?

    General and Desktop
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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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        • L
          lyuts last edited by

          Change the 19th line to

          @QSqlQuery query(db);@

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

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          • D
            doforumda last edited by

            same error again

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            • L
              lyuts last edited by

              Take a look into mysql logs to see what happens when you are trying to connect from your application.

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

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              • D
                doforumda last edited by

                how can i check that mysql logs and from where?

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                • L
                  lyuts last edited by

                  [quote author="doforumda" date="1286880547"]how can i check that mysql logs and from where? [/quote]

                  Try to find them:
                  @find /opt/lampp -name log -type d@

                  When you find the log directory, find a log for mysql and use tail utility:

                  @tail -f /path/to/mysql.log@

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

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                  • D
                    doforumda last edited by

                    this command didnt return something
                    @
                    root@zafar-laptop:/# find /opt/lampp -name log -type d
                    root@zafar-laptop:/#
                    @

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                    • D
                      doforumda last edited by

                      i have a folder inside lampp with the name logs. is it the one which your are talking about

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                      • L
                        lyuts last edited by

                        Solution 1:
                        @find /opt/lampp -name '*.log'@
                        This might need sudo'ing.

                        Solution 2:
                        If 1st fails then you need to find the config files for mysql (it should be located in /opt/lampp directory) and try to find out what is the location of mysql's log files.

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

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                        • D
                          doforumda last edited by

                          there are 6 files in there but no mysql.log

                          these are the files
                          access_log, cgisock.1693, error_log, httpd.pid, php_error_log, ssl_request_log

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                          • D
                            Dii last edited by

                            Don't bother with the log files, I guess Qt looks at the wrong place for the socket file...

                            Let's check this line in your mysql config file (my.cnf):

                            socket = /var/run/mysqld/mysqld.sock

                            You should find my.cnf in /etc/ or /etc/mysql/ ... I don't know ubuntu that much.

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                            • D
                              doforumda last edited by

                              1st solution returns this
                              @
                              root@zafar-laptop:/# find /opt/lampp -name *.log
                              /opt/lampp/htdocs/xampp/contrib/sqlnet.log
                              @

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                              • D
                                doforumda last edited by

                                with which editor i can view that .conf file. with gedit or something.

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                                • L
                                  lyuts last edited by

                                  [quote author="¤ Dii ¤" date="1286881470"]
                                  You should find my.cnf in /etc/ or /etc/mysql/ ... I don't know ubuntu that much.[/quote]

                                  I don't think that this config will be in /etc. He uses lampp - a preconfigured bundle. That config might be in /opt/lampp.

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

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                                  • D
                                    Dii last edited by

                                    BTW a quick sum:

                                    • mysql is installed
                                    • database and tables are created
                                    • access is granted
                                    • qt code looks fine

                                    I see two possibilities here: libmysqlclient is missing, or the socket file is at different place.

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                                    • D
                                      doforumda last edited by

                                      the file my.cnf is in etc/mysql folder

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                                      • D
                                        Dii last edited by

                                        doforumda: use gedit

                                        sudo gedit /etc/mysql/my.cnf

                                        at least most of the ubuntu machines have the config file there.

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                                        • D
                                          doforumda last edited by

                                          this is the socket line in my.cnf

                                          @
                                          socket = /var/run/mysqld/mysqld.sock
                                          @

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                                          • D
                                            Dii last edited by

                                            ok then the wrong socket guess was wrong... but let's make it sure:

                                            sudo ls -l /var/run/mysqld/*

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