QSqlQuery::prepare: no driver

rizoritis

Hello,

I am trying to update a row in my database however when I call the following function I get an error that says "QSqlQuery::prepare: no driver".

@void PointsModel::setCellData(int row, QString name, QString x, QString y, QString z, QString theta)
{
database->query->prepare("UPDATE points SET (name, x, y, z, a) VALUES (:name, :x, :y, :z, :a) WHERE id = :id");
database->query->bindValue(":id", row);
database->query->bindValue(":name", name);
database->query->bindValue(":x", x);
database->query->bindValue(":y", y);
database->query->bindValue(":z", z);
database->query->bindValue(":a", theta);
database->query->exec();
}@

I am doing other queries to the database such as SELECT, etc. So I don't know why this doesn't work. Any thoughts???

Thanks!

ChrisW67

At a guess, the database variable is pointing to a QSqlDatabase object that has not had QSqlDatabase::addDatabase() called on it beforehand.

Really though, you do not need to be persistently storing QSqlDatabase references or QSqlQuery objects, or allocating them on the heap in the first place.

rizoritis

[quote author="ChrisW67" date="1391220132"]At a guess, the database variable is pointing to a QSqlDatabase object that has not had QSqlDatabase::addDatabase() called on it beforehand.

Really though, you do not need to be persistently storing QSqlDatabase references or QSqlQuery objects, or allocating them on the heap in the first place.[/quote]

I did call addDatabase() in the constructor. I did the following:

@ db = QSqlDatabase::addDatabase( "QSQLITE" );
db.setDatabaseName( "../database" );

if ( !db.open() )
{
    qDebug() << "Failed to connect to database: " + db.lastError().text();
    return false;
}

qDebug() << "Successfully connected to database...";

query = new QSqlQuery(db);@

rizoritis

Just as an a test I implemented the following line before my queries to "re-register" the driver:

@database->query = new QSqlQuery(database->db);@

It got rid of the no driver error, however having to make a new query for each call I make doesnt seem right. Also, When looking into the database, it does not see to add anything to it, even if I call commit.

HNBeginner

@rizoritis i noticed that in qt: if you setdatabaseName and give it a correct path but with an incorrect database-name; qt creates an empty database and when you try to retrieve data in that database and because it is empty qt gives the error QSqlQuery::prepare: no driver: in short if you have an already existing database make sure you spell it correctly otherwise first create tables and then insert data in order to retrieve, update etc.