Qt 5 with SQLite: bindValue() results in "Parameter count mismatch" error

Question

I'm doing a simple parameterized query with Qt 5.3.1 (64-bit) on Windows 7 using the SQLite driver. When I use bindValue() to set the value of the single parameter of my query, I systematically get the dreaded "Parameter count mismatch" error. Everything works fine when I use addBindValue(). Note that the code with bindValue() works fine with Qt 4.8.5 (64-bit).

Here is the full code (main.cpp):

#include <QtSql>

int main(int, char* [])
{
    auto db = QSqlDatabase::addDatabase("QSQLITE");
    db.setDatabaseName("db.sqlite");
    db.open();

    {
        QSqlQuery query("CREATE TABLE IF NOT EXISTS hashes (filepath TEXT, modified INTEGER, hash TEXT)", db);
        query.exec();
    }

    QSqlQuery query("SELECT modified FROM hashes WHERE filepath = :fp", db);
    query.bindValue(":fp", "test.jpg");

    if (!query.exec())
        qDebug() << query.lastError();

    db.close();

    return 0;
}

QtCreator project file (qtsqltest.pro):

QT += core sql
TARGET = qtsqltest
TEMPLATE = app
SOURCES += main.cpp

Program output on my machine:

QSqlError("", "Parameter count mismatch", "")

Any idea?

Answer 1

I just found out that my question is a duplicate of this one and that the corresponding answer is correct.

It turns out that query strings passed to the constructor of QSqlQuery are executed immediately, as per the documentation.

It isn't clear why such queries are working fine with Qt 4.8.5, or why they do work with Qt 5.3.1 when using positional parameters (using ? placeholders) while they fail with named parameters (using : placeholders).