Do I need an SQL server to work with Qt's QtSql library?

Question

I am a beginner with Qt, so my question might be a bit basic.

My intention is to work with an ODBC database located in my hard drive. I have tried to open it with this code:

QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
db.setHostName("");
db.setDatabaseName("c:\\database.mdb");
bool ok = db.open();
QSqlQuery query;
query.exec("SELECT name FROM results WHERE tag>10");
while (query.next()) {
    QString name1 = query.value(0).toString();
    qDebug() << name1;
}

Now, the problem is that the program can't find the database, failing at the db.open() line. I suspect that Qt can't open a database directly, but instead has to deal with an SQL server. Is this so? If that's the case, I'd be grateful if you could give me some clues on how to go ahead, particularly regarding host name (is it localhost?).

Also, I am not sure of whether the path to the file must be included in DatabaseName.

PS: I have no problem shifting to a different kind of database/server, e.g. MySQL. So if your solution requires this, I'd be happy with it!

Thanks in advance

D

Answer 1

For future reference:

Just as Werne Strydom said, the argument of setDatabaseName is not the database file name, but the name of the ODBC datasource that points to your database. Therefore, you need to create an ODBC that points to your database.

The usual way to do this (in Windows) would be to go to Control Panel\System & security\Administrative tools\Data Sources (ODBC). But if you're in a 64-bit machine and want to work with a 32-bit driver, go instead to C:\windows\SysWOW64 and run odbcad32.exe

When you do this, a dialog opens (same dialog regardless of 64/32-bits). Here you create your ODBC, give it a name and link it to your actual database. In my case, as I am working with a local database, I used the "User DNS" tab.

Then, back in Qt, you put that ODBC name as argument for setDatabaseName. And it works! (Or it did for me...)

The new bit of code looks like:

QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
db.setHostName("localhost");
db.setDatabaseName("MyDataSource");
bool ok = db.open();
QSqlQuery query;
query.exec("SELECT name FROM results WHERE tag>10");
while (query.next()) {
    QString name1 = query.value(0).toString();
    qDebug() << name1;
}

where "MyDataSource" is the name I gave to the ODCB.

Answer 2

Unless you specifically need a Jet/MS Access format database for something else you'd be better off going with SQLite. Qt has SQLite support built-in (QSQLITE driver) - you just point it at the database file and go. No need to setup ODBC data sources or anything.

Answer 3

According to the documentation, you should set the setDatabaseName to the ODBC datasource. You then configure the ODBC datasource to point to the appropriate file.