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. C++ sqlite commit db after an update
Forum Updated to NodeBB v4.3 + New Features

C++ sqlite commit db after an update

Scheduled Pinned Locked Moved Solved General and Desktop
24 Posts 5 Posters 9.3k Views 2 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.
  • mrjjM mrjj

    well check return value of next() and exec()
    if false, there is no record.

    qDebug << "exec says:" << query2.exec();
    qDebug << "next says:" << query2.next();

    also use
    http://doc.qt.io/qt-5/qsqlquery.html#size

    to see how many u got from the SELECT.

    The code seems to lack all error handling or this is just simplified code to show?

    gfxxG Offline
    gfxxG Offline
    gfxx
    wrote on last edited by gfxx
    #15

    @mrjj

    this is just simplified code to show

    I try to insert qDebug on query exec and next ... also I try to change all queryxx.clear into .finish as suggested on this doc:
    link http://doc.qt.io/qt-5/qsqlquery.html

    regards
    giorgio

    bkt

    1 Reply Last reply
    1
    • mrjjM mrjj

      well check return value of next() and exec()
      if false, there is no record.

      qDebug << "exec says:" << query2.exec();
      qDebug << "next says:" << query2.next();

      also use
      http://doc.qt.io/qt-5/qsqlquery.html#size

      to see how many u got from the SELECT.

      The code seems to lack all error handling or this is just simplified code to show?

      gfxxG Offline
      gfxxG Offline
      gfxx
      wrote on last edited by
      #16

      @mrjj

      I emphasize this: SQlite Statement is correctly executed .... but I'm unable to make "SELECT MAX(my_id_table)....." ...select the result is relative to the last program session ... INSERT the current session are not seen ...

      My code:

      void mainwindow::xxx()
      {
      
      int frq1, frq2, frq4, tm1, tm2, tm3, tm4, tm5, tm6, tm7, tm8;
      
      QSqlQuery Csetp(db);
            Csetp.prepare("SELECT fq1, fq2, fq4, t1, t2, t3, t4 ,t5, t6, t7, t8 FROM defaultdata WHERE id_default =:id_default");
            Csetp.bindValue(":id_default", programNU);
            Csetp.exec();
            Csetp.next();
            frq1 = Csetp.value(0).toInt();
            frq2 = Csetp.value(1).toInt();
            frq4 = Csetp.value(2).toInt();
            tm1 = Csetp.value(3).toInt();
            tm2 = Csetp.value(4).toInt();
            tm3 = Csetp.value(5).toInt();
            tm4 = Csetp.value(6).toInt();
            tm5 = Csetp.value(7).toInt();
            tm6 = Csetp.value(8).toInt();
            tm7 = Csetp.value(9).toInt();
            tm8 = Csetp.value(10).toInt();
            //db.commit();
            Csetp.finish();
            db.commit();
      
            qDebug() << "Csetp.exec():   " << Csetp.exec();
            qDebug() << "Csetp.next():   " << Csetp.next();
            qDebug() << "error:   " << Csetp.lastError().text();
      
      /*do somethings ... */
      }
      
      void MainWindow::modifyPgr(int NRPGR, int f1M, int f2M, int f4M, int t1M, int t2M, int t3M, int t4M, int t5M, int t6M, int t7M, int t8M)
      {
      
          QSqlDatabase db;
          QSqlQuery queryM(db);
          queryM.prepare("UPDATE defaultdata SET id_default=:id_default, fq1=:fq1, fq2=:fq2, fq4=:fq4, t1=:t1, t2=:t2, t3=:t3, t4=:t4, t5=:t5, t6=:t6, t7=:t7, t8=:t8 WHERE id_default =:id_default");
          queryM.bindValue(":id_default", NRPGR );
          queryM.bindValue(":fq1",f1M);
          queryM.bindValue(":fq2",f2M);
          queryM.bindValue(":fq4",f4M);
          queryM.bindValue(":t1",t1M);
          queryM.bindValue(":t2",t2M);
          queryM.bindValue(":t3",t3M);
          queryM.bindValue(":t4",t4M);
          queryM.bindValue(":t5",t5M);
          queryM.bindValue(":t6",t6M);
          queryM.bindValue(":t7",t7M);
          queryM.bindValue(":t8",t8M);
          queryM.exec();
          queryM.next();
          //db.commit();
          queryM.finish();
          db.commit();
          qDebug() << "queryM:  " << queryM.lastError().text();
          qDebug() <<  "queryM-db: " << db.lastError().text();
      
      /* do somethings ....*/
      }
      
      
      *************************App Output*******************
      
      queryM:   " "
      queryM-db:  "Driver not loaded Driver not loaded"
      Csetp.exec():    true
      Csetp.next():    true
      error:    " "
      Csetp.exec():    true
      Csetp.next():    true
      error:    " "
      queryM:   " "
      queryM-db:  "Driver not loaded Driver not loaded"
      

      not understand -> "Driver not loaded Driver not loaded" ... library .so is loaded ... qtcreator plugin folder contain libqsqlite .so ... in my .pro file I add targhet to plugin folder of GCC64 containing libqsqlite .so .. I've these declaration on head:

      QT       += widgets\
      network widgets \
      qml quick\
      serialbus\
      concurrent widgets\
      sql\
      core\
      xml\
      opengl\
      gui
      

      not see where is the problem ....

      Regards
      Giorgio

      bkt

      1 Reply Last reply
      0
      • mrjjM Offline
        mrjjM Offline
        mrjj
        Lifetime Qt Champion
        wrote on last edited by
        #17

        Ok, but you check in a funny way
        ...
        Csetp.bindValue(":id_default", programNU);
        Csetp.exec(); <<< where is the check here?

        later u do
        qDebug() << "Csetp.exec(): " << Csetp.exec();

        but thats another exec() so its not really solid.

        also you call db.commit(); but where is the start of it ?
        http://doc.qt.io/qt-4.8/qsqldatabase.html#commit

        but maybe it all comes from
        "Driver not loaded Driver not loaded"
        Normally , you do not link to any extern .SO files to use SQL.
        QT += SQL should be enough :)

        gfxxG 1 Reply Last reply
        1
        • mrjjM mrjj

          Ok, but you check in a funny way
          ...
          Csetp.bindValue(":id_default", programNU);
          Csetp.exec(); <<< where is the check here?

          later u do
          qDebug() << "Csetp.exec(): " << Csetp.exec();

          but thats another exec() so its not really solid.

          also you call db.commit(); but where is the start of it ?
          http://doc.qt.io/qt-4.8/qsqldatabase.html#commit

          but maybe it all comes from
          "Driver not loaded Driver not loaded"
          Normally , you do not link to any extern .SO files to use SQL.
          QT += SQL should be enough :)

          gfxxG Offline
          gfxxG Offline
          gfxx
          wrote on last edited by
          #18

          @mrjj ```
          QSqlDatabase db;
          QSqlQuery Csetp(db);
          Csetp.prepare("SELECT fq1, fq2, fq4, t1, t2, t3, t4 ,t5, t6, t7, t8 FROM defaultdata WHERE id_default =:id_default");
          Csetp.bindValue(":id_default", programNU);
          qDebug() << "Csetp.exec(): " << Csetp.exec();
          qDebug() << "Csetp.next(): " << Csetp.next();
          qDebug() << "error: " << Csetp.lastError().text();
          frq1 = Csetp.value(0).toInt();
          frq2 = Csetp.value(1).toInt();
          frq4 = Csetp.value(2).toInt();
          tm1 = Csetp.value(3).toInt();
          tm2 = Csetp.value(4).toInt();
          tm3 = Csetp.value(5).toInt();
          tm4 = Csetp.value(6).toInt();
          tm5 = Csetp.value(7).toInt();
          tm6 = Csetp.value(8).toInt();
          tm7 = Csetp.value(9).toInt();
          tm8 = Csetp.value(10).toInt();
          //db.commit();
          Csetp.finish();
          db.commit();

          *****output

          Csetp.exec(): true
          Csetp.next(): true
          error: " "

          
          you are in right ... but result not change..
          
          Regards
          Giorgio

          bkt

          1 Reply Last reply
          0
          • gfxxG Offline
            gfxxG Offline
            gfxx
            wrote on last edited by gfxx
            #19
            QSqlDatabase db;
                  QSqlQuery Csetp(db);
                  Csetp.prepare("SELECT fq1, fq2, fq4, t1, t2, t3, t4 ,t5, t6, t7, t8 FROM defaultdata WHERE id_default =:id_default");
                  Csetp.bindValue(":id_default", programNU);
                  qDebug() << "Csetp.exec():   " << Csetp.exec();
                  qDebug() << "Csetp.next():   " << Csetp.next();
                  qDebug() << "error:   " << Csetp.lastError().text();
                  frq1 = Csetp.value(0).toInt();
                  frq2 = Csetp.value(1).toInt();
                  frq4 = Csetp.value(2).toInt();
                  tm1 = Csetp.value(3).toInt();
                  tm2 = Csetp.value(4).toInt();
                  tm3 = Csetp.value(5).toInt();
                  tm4 = Csetp.value(6).toInt();
                  tm5 = Csetp.value(7).toInt();
                  tm6 = Csetp.value(8).toInt();
                  tm7 = Csetp.value(9).toInt();
                  tm8 = Csetp.value(10).toInt();
                  //db.commit();
                  Csetp.finish();
                  //db.commit();
                  qDebug() << "error db on Csetp:   " << db.lastError().text();
            
            ***********************output without commit()****************
            Csetp.exec():    true
            Csetp.next():    true
            error:    " "
            error db on Csetp:    "Driver not loaded Driver not loaded"
            

            add INCLUDEPATH at libsqlite.so is my last chance to try to solve to myself the "impossible error": "Driver not loaded Driver not loaded" ....

            but now I try community help...

            Regards
            Giorgio

            bkt

            1 Reply Last reply
            0
            • mrjjM Offline
              mrjjM Offline
              mrjj
              Lifetime Qt Champion
              wrote on last edited by
              #20

              Hi
              did you also check with

              qDebug() << "number of rows: " << Csetp.size();

              just to know?

              gfxxG 1 Reply Last reply
              0
              • mrjjM mrjj

                Hi
                did you also check with

                qDebug() << "number of rows: " << Csetp.size();

                just to know?

                gfxxG Offline
                gfxxG Offline
                gfxx
                wrote on last edited by
                #21

                @mrjj

                QSqlDatabase db;
                      QSqlQuery Csetp(db);
                      Csetp.prepare("SELECT fq1, fq2, fq4, t1, t2, t3, t4 ,t5, t6, t7, t8 FROM defaultdata WHERE id_default =:id_default");
                      Csetp.bindValue(":id_default", programNU);
                      qDebug() << "Csetp.exec():   " << Csetp.exec();
                      //qDebug() << "number of rows: " << Csetp.size();
                      qDebug() << "Csetp.next():   " << Csetp.next();
                      qDebug() << "error:   " << Csetp.lastError().text();
                      //qDebug() << "number of rows: " << Csetp.size();
                      frq1 = Csetp.value(0).toInt();
                      frq2 = Csetp.value(1).toInt();
                      frq4 = Csetp.value(2).toInt();
                      tm1 = Csetp.value(3).toInt();
                      tm2 = Csetp.value(4).toInt();
                      tm3 = Csetp.value(5).toInt();
                      tm4 = Csetp.value(6).toInt();
                      tm5 = Csetp.value(7).toInt();
                      tm6 = Csetp.value(8).toInt();
                      tm7 = Csetp.value(9).toInt();
                      tm8 = Csetp.value(10).toInt();
                      qDebug() << "number of rows: " << Csetp.size();
                      //db.commit();
                      Csetp.finish();
                      //db.commit();
                      qDebug() << "error db on Csetp:   " << db.lastError().text();
                
                *******************output****************************
                
                Csetp.exec():    true
                Csetp.next():    true
                error:    " "
                number of rows:  -1   /*<-------??????*/
                error db on Csetp:    "Driver not loaded Driver not loaded"
                

                from doc: field 0 is forename and field 1 is surname. Using SELECT * is not recommended because the order of the fields in the query is undefined.

                so I try with other query...

                QSqlDatabase db;
                    QSqlQuery queryM(db);
                    queryM.prepare("UPDATE defaultdata SET id_default=:id_default, fq1=:fq1, fq2=:fq2, fq4=:fq4, t1=:t1, t2=:t2, t3=:t3, t4=:t4, t5=:t5, t6=:t6, t7=:t7, t8=:t8 WHERE id_default =:id_default");
                    queryM.bindValue(":id_default", NRPGR );
                    queryM.bindValue(":fq1",f1M);
                    queryM.bindValue(":fq2",f2M);
                    queryM.bindValue(":fq4",f4M);
                    queryM.bindValue(":t1",t1M);
                    queryM.bindValue(":t2",t2M);
                    queryM.bindValue(":t3",t3M);
                    queryM.bindValue(":t4",t4M);
                    queryM.bindValue(":t5",t5M);
                    queryM.bindValue(":t6",t6M);
                    queryM.bindValue(":t7",t7M);
                    queryM.bindValue(":t8",t8M);
                    queryM.exec();
                    qDebug() << "queryM size:  " << queryM.size();
                    queryM.next();
                    //db.commit();
                    queryM.finish();
                    db.commit();
                    qDebug() << "queryM:  " << queryM.lastError().text();
                    qDebug() <<  "queryM-db: " << db.lastError().text();
                *******************output****************************
                queryM size:   -1
                queryM:   " "
                queryM-db:  "Driver not loaded Driver not loaded"
                

                So it seems not see valid statement but it exec it (i control the new data in db with sqliteman gui after suthdown of my application. The result is always ok!!!!!).

                But for me is impossible to use with success SELECT MAX(id_xxx) ...
                and I have these terrible error "Driver not loaded Driver not loaded" (I seem to live in a film of horrors where the monster always comes out from behind the corner ...)

                regards
                Giorgio

                bkt

                1 Reply Last reply
                0
                • mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by mrjj
                  #22

                  @gfxx said:

                  QSqlDatabase db;

                  Make sure you dont have multiple
                  QSqlDatabase db around in code.
                  Just have 1 in class that last the life time of the application.

                  So your UPDATE works but you SELECT returns nothing.

                  • (I seem to live in a film of horrors where the monster always comes out from behind the corner ...)
                    Good news is that most of the time, the monsters die and hero survives :)
                  gfxxG 1 Reply Last reply
                  0
                  • mrjjM mrjj

                    @gfxx said:

                    QSqlDatabase db;

                    Make sure you dont have multiple
                    QSqlDatabase db around in code.
                    Just have 1 in class that last the life time of the application.

                    So your UPDATE works but you SELECT returns nothing.

                    • (I seem to live in a film of horrors where the monster always comes out from behind the corner ...)
                      Good news is that most of the time, the monsters die and hero survives :)
                    gfxxG Offline
                    gfxxG Offline
                    gfxx
                    wrote on last edited by
                    #23

                    @mrjj

                    news .... query.lasterror.text()

                    "cannot commit - no transaction is active Unable to commit transaction"
                    

                    Make sure you dont have multiple
                    QSqlDatabase db around in code.

                    eureka!!

                    I write only 4 app in qt with database ... The first is managing data from sensors ... What I have many updates and inserts, and many SELECT MAX ... other times it was enough to save the data before the shutdown .... so I never explored the use QSqldatabase ... I always put everything in mainwindows ...

                    thanks a lot

                    edit ... commit command is not necessary .... somewho it suggested my to use it in old app (3 years ago in QT4.x) ... only today I see the real work of these command ...

                    Best Regards
                    Giorgio

                    I would say that the hero is you today .... next time I hope to be me .... thanks :)

                    bkt

                    1 Reply Last reply
                    1
                    • mrjjM Offline
                      mrjjM Offline
                      mrjj
                      Lifetime Qt Champion
                      wrote on last edited by
                      #24

                      Super :)
                      To use commit, one should start with
                      bool QSqlDatabase::transaction()
                      first. Else commit is not valid.

                      Happy coding :)

                      1 Reply Last reply
                      1

                      • Login

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