C++ sqlite commit db after an update

gfxx

QSqlDatabase db;

    QSqlQuery query2(db);
    query2.prepare("SELECT MAX(id_stc) FROM stc ");
    query2.exec();
    query2.next();
    index2 = query2.value(0).toInt();
    query2.clear();

    QSqlQuery query21(db);
    query21.prepare("UPDATE stc SET id_st=:id_st, h_on=:h_on, h_off=:h_off, err_m=:err_m, t_em=:t_em, t_pause=:t_pause, p_pro=:p_pro WHERE id_st =:id_st");
    query21.bindValue(":id_st", index2 );
    query21.bindValue(":h_on", HOn);
    query21.bindValue(":h_off", HOff);
    query21.bindValue(":err_m", errM);
    query21.bindValue(":t_em", tEme);
    query21.bindValue(":t_pause", tPa);
    query21.bindValue(":p_pro", pPro);
    query21.exec();
    query21.next();
/*db.commit(); ... if I put the commit command here is the same*/
    query21.clear();
    db.commit();

my piece of code .... it works great but if I make an insert with other void (myINSERTvoid) I can't able to make an UPDATE on real last roid .... If stop my app and run again i can see last roid and make correctly the UPDATE .... obviusly if make an INSERT statement first and an UPDATE second the problem comes out again ....

I'm on linux ubuntu 14.04 ... with sqlite3 ... I just install all dependancy and if I insert 1 row for control driver ...

qDebug ( )  <<  QSqlDatabase::drivers();

I obtain the correct response .....

I have some problem but not see it...

Thanks for any helps

Regards
Giorgio

the_

@gfxx

commit() ends a transaction, but I can't see where you start your transaction.

//Edit
What do you get with db.lastError(); ?

VRonin

This post is deleted!

gfxx

@the_

"Driver not loaded Driver not loaded"

why?????

Regards
Giorgio

gfxx

@VRonin

Thanks for your interest .... but having a personal translator does not help my poor English ....

Regards
Giorgio

VRonin

Did you deploy the driver plugin? qsqlite.dll

gfxx

I'm on linux .....

Regards
Giorgio

gfxx

Pieces of code when I open my db...

QPluginLoader loader("/home/myhome/Qt/5.6/gcc_64/plugins/sqldrivers/libqsqlite.so");
                loader.load();
                qDebug() << loader.errorString(); /*1 mess*/


QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
//QSqlDatabase(QSqlDatabase::addDatabase("QSQLITE"));
                db.setDatabaseName( "/home/myhome/Qt/BDB/mydb.sqlite" );
                 
 if( !db.open() )
                    {
                               /*my ERROR CONNECTION messages*/
                    }
else{
                        qDebug() << db.lastError().text();/*2 mess*/
                    }
                     qDebug() << db.lastError().text();/*3 mess*/

                    qDebug ( )  <<  QSqlDatabase::drivers();/*4 mess*/

debug messages .....

/*1 mess*/ "Unknown error"
/*2 mess*/ " "
/*3 mess*/ " "
/*4 mess*/ ("QSQLITE", "QMYSQL", "QMYSQL3", "QPSQL", "QPSQL7")

Wurgl

@gfxx QSqlDatabase("QSQLITE") ist enough. No QPluginloader is needed.

Of course, yo need to set the name of the database (with sqlite it is the filename)
setDatabaseName("your-db-name.sqlite");
and you need to open() the database.

gfxx

/*QPluginLoader loader("/home/myhome/Qt/5.6/gcc_64/plugins/sqldrivers/libqsqlite.so");
                loader.load();
                qDebug() << loader.errorString(); */


QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
//QSqlDatabase(QSqlDatabase::addDatabase("QSQLITE"));
                db.setDatabaseName( "/home/myhome/Qt/BDB/mydb.sqlite" ); /*<---- 
not work I've created mydb with Sqliteman ... 
and save it without extension ... so work only if I write "/home/myhome/Qt/BDB/mydb"  */
                 
 if( !db.open() )
                    {
                               /*my ERROR CONNECTION messages*/
                    }
else{
                        qDebug() << db.lastError().text();/*2 mess*/
                    }
                     qDebug() << db.lastError().text();/*3 mess*/

                    qDebug ( )  <<  QSqlDatabase::drivers();/*4 mess*/

with mydb.sqlite obtain these error:

QSqlQuery::value: not positioned on a valid record
QSqlQuery::value: not positioned on a valid record ....

regards
Giorgio

gfxx

no new with suggested way..

regards
Giorgio

mrjj

@gfxx said:

QSqlQuery::value: not positioned on a valid record ....

That could mean you try to read from QSqlQuery before calling next/ check if it is valid.
Please look at doc and samples how to use it correctly
http://doc.qt.io/qt-5/qsqlquery.html

  QSqlQuery query("SELECT country FROM artist");
    while (query.next()) {
        QString country = query.value(0).toString();
        doSomething(country);
    }

gfxx

QSqlDatabase db;

    QSqlQuery query2(db);
    query2.prepare("SELECT MAX(id_stc) FROM stc ");
    query2.exec();
    query2.next();
    index2 = query2.value(0).toInt();
    query2.clear();
db.commit();

this is my query ...

I'm sorry I can not tell the difference with this, my query ...

regards
Giorgio

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?

gfxx

@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

gfxx

@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

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 :)

gfxx

@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

gfxx

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

mrjj

Hi
did you also check with

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

just to know?