Building QT with "windeployqt": not connect to database (ODBC)

AndreaCT · wrote on 4 May 2020, 14:47

Hello, and sorry for my not perfect English.

I developed a simple UI application with QT, connected to a local database (using XAMPP). I downloaded the ODBC connector (https://dev.mysql.com/downloads/connector/odbc) and configured the connection to the database through ODBC Data Sources. In the main I connect to the database and everything works correctly.

Then I generated the executable of my project and related dependencies using the windeployqt command from terminal. I put all in the same folder and the executable works perfectly.

Then I moved everything (exe + dependencies) to another PC (with the same database locally and xampp running), but here the connection to the database fails.

How can I solve it? Thanks!

SGaist · wrote on 4 May 2020, 15:52

Hi and welcome to devnet,

Did you check that you also deployed the connector's dll and its dependencies along with your application ?

AndreaCT · wrote on 4 May 2020, 18:10

That's all! Into sqldrivers there is qsqlodbc.dll

SGaist · wrote on 4 May 2020, 18:12

Use a tool like Dependency Walker to find the direct dependencies you need to deploy.

AndreaCT · wrote on 4 May 2020, 20:21

Mmh this is the output:

How can recognize and integrate the direct dependencies?

SGaist · wrote on 4 May 2020, 20:28

This is for your application executable, you should check the database plugin.

AndreaCT · wrote on 4 May 2020, 20:45

Mmh so I don't have to open my exe in dependency walker?
Sorry and thank you for your patience...

AndreaCT · wrote on 4 May 2020, 20:56

C:\Qt\5.14.2\mingw73_32\plugins\sqldrivers\qsqlodbc.dll
I have to run dependency walker on it, right?

AndreaCT · wrote on 4 May 2020, 21:33

Eventually, this is the output:

These are already present:

LIBGCC_S_DW2-1.DLL
LIBSTDC++-6.DLL
QT5CORE.DLL
QT5SQL.DLL

I downloaded the other 3 [https://www.dll-files.com/search.dll.html], and added these in the same folder.

SGaist · wrote on 5 May 2020, 19:14

And the ODBC dll ?

AndreaCT · wrote on 5 May 2020, 19:32

ODBC32.dll, no?

SGaist · wrote on 5 May 2020, 19:50

Yes, did you check the dependencies of that one ?

AndreaCT · wrote on 5 May 2020, 20:00

Download and put inside all the missing dll?

AndreaCT · wrote on 5 May 2020, 20:18

Unfortunately the problem persists

hskoglund · wrote on 5 May 2020, 20:45

Hi, just guessing, are you using 127.0.0.1 (or localhost) to connect to the database also on the new PC? Also, have you checked that you can reach the database with MySQL workbench?

AndreaCT · wrote on 5 May 2020, 21:07

Yes to both

hskoglund · 6 May 2020, 09:04

Ok. Is it same version of Windows 10 on both computers?

JSher · wrote on 6 May 2020, 01:08

Is the ODCB connection created on 2nd computer? Also with mysql connector you need Visual C++2015 distro.

--James

AndreaCT · replied to hskoglund on 6 May 2020, 09:04

@hskoglund Yes

AndreaCT · wrote on 6 May 2020, 09:15

@JSher No, I just tried to print the error on a label with db.lastError() and the output is: "[Microsoft][Driver Manager ODBC] Nome origine dati non trovato e driver predefinito non specificato. QODBC3: Unable to connect"