Connecting to an ODBC Data Source

[kikapu]

Hi to all folks here.

i am trying to open a QSqlDatabase connection to an Sql Server of mine. I have created an ODBC data source callded "herc" in the Windows and wrote this code:

from PyQt4 import QtSql

db = QtSql.QSqlDatabase.addDatabase("QODBC");
db.setDatabaseName("herc");
db.setUserName("sa");
db.setPassword("the paswsword");
ok = db.open();

but i receive: "QSqlDatabase: QODBC3 driver not loaded
QSqlDatabase: available drivers: "

I am using Qt4.2 Open Source edition, i read the docs and i think that the above is correct. Do i have to do something else too to have this thing work ??

Thanks a lot for any help!

[kikapu]

Anyone ??

Is it something to do with the OpenSource version of Qt that i use ??

[kikapu]

I think, not much people are doing DB stuff here...:)

Anyway, i found something that a plugn must be create frst so the whole thing could work and i did this (from trolltech):

cd %QTDIR%\src\plugins\sqldrivers\odbc
qmake -o Makefile odbc.pro
nmake

so it did write a file to c:\Qt\4.2.3\src\plugins\sqldrivers\libqsqlodbc.a
but how can i use this ?? The page talks about "loading" the plugin but how i can atually load this and have db code to work ?

Client libraries for Sql Server are available on my machine, so now what ? :confused:

EDIT: i also see in the same directory that a qsqlodbc.dll is created.I tried to copy that dll into the bin directory of QT but the result is the same.

I somehow miss the how i can "load" this plugin...

[jacek]

Can you see QODBC driver when you start the sqlbrowser demo?

[kikapu]

Hey jacek,

thanks for the reply!

Yes, i see the QODBC driver and in fact, i can fetch tables in the SqlBrowser demo (!), based on the odbc connection i have already declared in windows (i called it "pm").
The code that i wrote is still give me the same error:

QSqlDatabase: QODBC driver not loaded
QSqlDatabase: available drivers:


Have you any idea about this ??

The code is here (notice that i have already tried with both Connection String and ODBC dns ways...)


from PyQt4 import QtCore, QtSql

db = QtSql.QSqlDatabase.addDatabase("QODBC");
db.setHostName("localhost");
#db.setDatabaseName("DRIVER={SQL #Server};SERVER=localhost;DATABASE=playmates;UID=s a;PWD=the password");
db.setDatabaseName("pm");
db.setUserName("sa");
db.setPassword("the password");
f = db.open()

[jacek]

In what directory the Qt DLLs that PyQt4 uses are located?

[kikapu]

In what directory the Qt DLLs that PyQt4 uses are located?

Hmm...i am not sure i understand. If you mean the whole bunch of Qt dll, they are in c:\qt\4.2.3\bin
If you mean the .pyd that PyQt uses, it's at c:\Python2.5\lib\site-packages\PyQt4. There i see the QtCore.pyd, QtGui.pyd etc.

[kikapu]

Hi jacek,

i found from here:
http://www.qtcentre.org/forum/p-qsqldatabase-qmysql-driver-not-loaded-post18045/postcount6.html

a post of yours to a folk that had the same problem and finally i have the solution:
I have to "create a QApplication first"...

When i put the line


app = QtGui.QApplication(sys.argv)

everything works as expected! :)

I cannot figure out why this is required but i will guess that plugins are loaded that way and thus is the recommened way to code it.
Also, i delete the qsqlodbc.dll fro \Qt\4.2.3\bin as it seems that is not needed. I'lhave to check if it is required by my program when i want to deploy it to another machine.

Thanks for the help!

[jacek]

I cannot figure out why this is required but i will guess that plugins are loaded that way and thus is the recommened way to code it.
QApplication (or QCoreApplication) is required for every Qt-based application, because it's resposible for initialization of the whole framework. One of the things it does is loading the plugins.

[kikapu]

Just out of curiocity :

The odbc entry i have made in Windows Control Panel "ODBC Data Source Administrator",is working ok when i set it to point at a database at my local host.

The code


db.setDatabaseName("pm");

is the only thing i need to connect to the server.

But when that odbc entry is point to a network server, it does not work. It requires the commands


db.setUserName("sa");
db.setPassword("password");


so it can work and connect.

I trapped the db.lastError() and it gives me :

[Microsoft][ODBC SQL Server Driver][SQL Server]Login failed for user '(null)'. Reason: Not associated with a trusted SQL Server connection. QODBC3: Unable to connect

It seems that it somehow does not retain the credentials that i've correctly declared.
Am i missing something ??