@dviktor I looked at your "minimal" repro. The queries are horrendously long and complex, and require many tables with many columns. If I were you and I wanted help/someone to look at it I would spend my time reducing to an absolute minimum, e.g. does it require a JOIN at all, does it show up with one JOIN, do I really need a calculated column, do I need MAX() or other "aggregate", does it matter whether a column is DATE versus DATETIME, does the WHERE clause matter, etc. I would hope to produce the absolute minimum code and database where I could say: "if you run this query it works fine but as soon as I make just this one little change it goes wrong". Up to you.

@Christian-Ehrlicher said in QSql performance consideration/data flow design.: Ok, I would never consider those functions as replacement for stored procedure. I agree, but it is their documentation, I guess "Lite" means "lite" :)

May be you missed creating the someSqlModel object itself ? Is someSqlModel local object ?

Do you use Qt6. 7 on win11? Then you are probably using the windows 11 style.

@Donald9307 Just to clear the confusion, do you have any model or in which way do you use your query? Because there is no QSqlQuery::setQuery() (as in the title). But good to hear that it worked for you :)

I have worked with the qsqlcipher plugins well and gone through with the qsqlcipher plugin code and I puted some print statement in the plugin code itself then observed that the fetchNext function taking is more time, Please look into it

@RyanSolanki Please mark as solved if you are happy the issue is resolved. Also consider reading up further about Qt's memory management model (maybe it would make sense to pass a parent during the QSqlQueryModel's construction to avoid all that manual memory management or else perhaps smart pointers if there is no clear parent to assign ownership to). Furthermore, SGaist's point about passing a pointer to a function whose signature expects a const reference cannot be understated. If the function expects a pointer, give it a pointer. If it expects a const reference, give it an object created on the stack! https://doc.qt.io/qt-5/qsqlquerymodel.html#details The documentation is good; use it! It is unclear to me why you are using functions such as "clear" for the model. The setQuery() function already clears the model. Why mess around with new and delete several times when you can just pass in a new query to modify the existing model? Futhermore, why bother clear()-ing the model immediately before you delete it? The destructor is called during the delete, which itself frees up any resources, per the documentation. There are deeper problems of comprehension going on here!

@Christian-Ehrlicher Yep. QIdentityProxyModel works fine. Thanks.

@hobbyProgrammer You cannot have a combo which is both bound to a model and has some extra row inserted into it --- it's one or the other. There are several possible approaches: Make your SQL query return a UNION ALL which includes a literal <select> as an extra row. Not really nice, because it makes the <select> be an extra row from the query. Copy the result set from the query into another model (you probably only need a list, perhaps a QStringList) where you insert the extra <select> as an item and use that as the combo's model. If you don't get a better example, this is the most obvious to code. Interpose a QIdentityProxyModel between the query model and the combo, and add the extra row there. I suspect this is the way it's supposed to be done(?).

@christian-ehrlicher said in What to subclass?: Especially compared to the idea to parse the data somehow from a sqlite file Where I have said that? :) I never had the idea to "parse" the sqlite file directly. I will try to get the data with a query first and see what I can do with it :) (I guess QSqlResult is the key?!)

So I tried the suggestions by @jwernerny. I dumped the QSqlQueryModel and went with a QStandardItemModel. TableView now displays correctly. Code now looks like this: void MainWindow::on_btnLoadTable_clicked() { conn = new Connection("LOCALHOST\\SQLEXPRESS", "Plants"); stdModel = new QStandardItemModel(this); conn->init(); //Set driver and connection options conn->open(); qry1 = new QSqlQuery(conn->db); const int COL_COUNT = 3; if (qry1->exec("spBatchesPerPlant")) { qDebug() << "Executing query..."; int row = 0; //used for counting rows in the query while (qry1->next()) //Loop through the results { for (int col = 0; col < COL_COUNT; col++) { stdItem = new QStandardItem(qry1->value(col).toString()); stdModel->setItem(row, col, stdItem); } row++; } ui->tableView->setModel(stdModel); } } Motto of the story: stored procedures generate forward only queries. QSqlQueryModel does not work for forward only queries, so use a standard item (or custom) model.

Hi, Add a setter to your model that is Q_INVOKABLE and pass your query through it. Don't forget to add proper error checking to give feedback to your user if something goes wrong.

Hi, There’s also no need to allocate the query on the heap as the QSqlQueryModel::setQuery method parameter suggests.

Hi and welcome to devnet, You can use a proxy model that adds the columns you want/need. You can keep updating the DB content and trigger the GUI update at some known interval or when a certains amount of changed happened to the database.

@Cleiton-Bueno Yes. If the query string is correct it will work.

Można użyć modelu proxy, który będzie interpretował jakieś dane (np. "0" i "1") jako checkbox, np. class MyProxy : public QIdentityProxyModel { public: MyProxy(QObject* parent) : QIdentityProxyModel(parent) {} QVariant data(const QModelIndex& index, int role) const override { if (role == Qt::CheckStateRole && index.column() == 0) { QString str_value = QIdentityProxyModel::data(index, Qt::DisplayRole).toString(); return (str_value == "1") ? Qt::Checked : Qt::Unchecked; } return QIdentityProxyModel::data(index, role); } bool setData(const QModelIndex& index, const QVariant& value, int role) override { if (role == Qt::CheckStateRole && index.column() == 0) { QString str_value = (value.toInt() == Qt::Checked) ? "1" : "0"; return QIdentityProxyModel::setData(index, str_value, Qt::EditRole); } else return QIdentityProxyModel::setData(index, value, role); } Qt::ItemFlags flags(const QModelIndex& index) const override { Qt::ItemFlags f = QIdentityProxyModel::flags(index); if (index.column() == 0) f |= Qt::ItemIsUserCheckable; return f; } }; oczywiście numer kolumny i dane rozpoznawane jako "zaznaczony" można sobie dostosować. Takiego modelu można użyć potem tak: QSqlTableModel* model = new QSqlTableModel(parent, database); MyProxy* proxy = new MyProxy(parent); proxy->setSourceModel(model); tableView->setModel(proxy);

@_compiler Model *derived = static_cast<QSqlQueryModel*>(model); This isn't a valid cast because you can't implicitly cast to a derived type (see @mrjj's comment). Model *derived = static_cast<Model *>(model); Is valid but unsafe, as @SGaist pointed out. Ultimately, what is not working?

Yeah, according to QComboBox code should work: QVariant QComboBox::itemData(int index, int role) const { Q_D(const QComboBox); QModelIndex mi = d->model->index(index, d->modelColumn, d->root); return d->model->data(mi, role); } Will implement this.