QSqlQuery::executedQuery() does not return a prepared query with SQLite

l3u_

Hi :-)

I use QSqlQuery::executedQuery() for debugging purposes. The docs say:

The placeholders in the original query are replaced with their bound values to form a new query. This function returns the modified query.

If I understand this correctly, a query like UPDATE config SET value = ? WHERE key = ? with foo and bar as bound values should be returned as UPDATE config SET value = 'foo' WHERE key = 'bar' or similar, shouldn't it? Instead, I always get the "original" query with the ? characters unchanged.

Am I missing something or is this a bug? I use Qt 5.9.4.

mrjj

Hi
Might be a silly question, but it did execute correctly ?

JonB

@l3u_ said in QSqlQuery::executedQuery() does not return a prepared query with SQLite:

QSqlQuery::executedQuery

http://www.qtcentre.org/threads/57676-QSqlQuery-executedQuery-()-Bound-values-versus-place-holders

l3u_

@mrjj It did!

l3u_

@JonB Thanks for the link! The initial post asks the same question as I do here – but they talk about replication and inserting queries into another database later on, so I think the question (bug or feature or misread docs) is not answered there. Or did I miss something there?

Christian Ehrlicher

Please provide a minimal, compilable example so we can reproduce the issue. There are many things which can go wrong here...

JonB

@l3u_
Yes, I think I quoted it just for its explanation of what the behaviour should be under what circumstances.

So, just to be 100% clear because I don't see you've stated it above explicitly: when do you examine QSqlQuery::executedQuery() in your code? It only claims to do the substitution (if at all) after it has executed the query.

l3u_

Here we go. I took a modified "Hello world" program to make clear what I mean (assuming there's no "test.db" file where the program is executed):

main.cpp:

#include "MainWindow.h"
#include <QApplication>

int main(int argc, char* argv[])
{
    QApplication app(argc, argv);
    MainWindow mainWindow;
    mainWindow.show();
    return app.exec();
}

MainWindow.h:

#include <QMainWindow>

class MainWindow : public QMainWindow
{

public:
    MainWindow();
    
};

MainWindow.cpp:

#include "MainWindow.h"

#include <QSqlDatabase>
#include <QSqlQuery>
#include <QDebug>

MainWindow::MainWindow()
{
    QSqlDatabase db;
    db = QSqlDatabase::addDatabase(QString::fromUtf8("QSQLITE"), QString::fromUtf8("SQLiteDB"));
    db.setDatabaseName(QString::fromUtf8("test.db"));
    db.open();

    QSqlQuery query(db);
    query.exec(QString::fromUtf8("CREATE TABLE config(key TEXT, value TEXT)"));

    query.prepare(QString::fromUtf8("INSERT INTO config(key, value) VALUES(?, ?)"));
    query.bindValue(0, QString::fromUtf8("foo"));
    query.bindValue(1, QString::fromUtf8("bar"));
    query.exec();

    qDebug() << query.executedQuery();

    db.close();
}

Output (notice the unsubstituted "?" characters):

"INSERT INTO config(key, value) VALUES(?, ?)"

Control:

$ sqlite3 test.db "SELECT * FROM config"
foo|bar