Installing MS SQL ODBC Driver under Linux and building the plug-in for Qt 5.9

A few days ago, the question arose of writing a console application that will work on Linux CentOS 7 and interact with MS SQL Server 2012. I really like Qt and I decided that I would use it to solve this problem. And if under Windows I quickly set up the necessary environment, then under Linux I ran into problems that were very difficult to solve using googling. I devoted one and a half days to this issue. I consider it useful to share my experience, perhaps it will help someone save valuable time.

Instruments

I do not want to pull the Qt sources to the server in order to build the plugin and the application itself. Therefore, I take the CentOS 7 LiveGNOME image and install it on the VirtualBox machine. After doing a full update, and put VirtualBox Guest Additions .

Install g ++:

sudo yum install gcc-c++

Downloading the Qt installer for Linux x64. I install Qt 5.9.1, additionally during installation I select the Source checkbox to get the sources.

Install Microsoft ODBC Driver for SQL Server

According to the instructions, I install the driver:

sudo su
curl https://packages.microsoft.com/config/rhel/7/prod.repo > /etc/yum.repos.d/mssql-release.repo
exit
sudo yum remove unixODBC-utf16 unixODBC-utf16-devel
sudo ACCEPT_EULA=Y yum install msodbcsql
sudo ACCEPT_EULA=Y yum install mssql-tools
echo 'export PATH="$PATH:/opt/mssql-tools/bin"' >> ~/.bash_profile
echo 'export PATH="$PATH:/opt/mssql-tools/bin"' >> ~/.bashrc
source ~/.bashrc
sudo yum install unixODBC-devel

The driver needs to be installed both on VirtualBox and on the machine where the software will work.

Build Qt QODBC Plugin

Following the instructions , download unixODBC somewhere , unpack it. Now we need to compile unixODBC and install. In the Qt documentation, as well as in other sources, I mostly saw examples that suggested installing unixODBC in / usr / local / unixODBC. This is a matter of taste, of course, but I will use just such an arrangement. Also, I want to put the driver config files in / usr / local / etc. To do this, you need to configure unixODBC with the following parameters:

./configure --prefix=/usr/local/unixODBC --sysconfdir=/usr/local/etc

Then we collect and install:

make
make install

Now you need to configure the Microsoft ODBC Driver for SQL Server. To do this, go to / usr / local / unixODBC / bin and execute:

sudo ./odbcinst -i -d -f /opt/microsoft/msodbcsql/etc/odbcinst.ini

If you installed the driver as described above, then the location of the odbcinst.ini file will be exactly that. Otherwise, you need to determine your path. All these steps need to be performed both on the Virtualbox machine and on the working one.

Now you need to build a Qt plugin to work with the ODBC driver. And from this moment, problems begin that are partially related to a bug that has not yet been fixed. In order to assemble the plugin you will have to apply some crutches. If someone has a more elegant version of a crutch, please write in the comments.

So, for assembly under normal conditions, we need to perform a simple procedure. Go to QT_DIR / 5.9.1 / Src / qtbase / src / plugins / sqldrivers / odbc and execute:

qmake "INCLUDEPATH+=/usr/local/unixODBC/include" "LIBS+=-L/usr/local/unixODBC/lib -lodbc"
make
make install

But due to the fact that we have a bug, most likely you will get an error:

Cannot read QT_DIR/5.9.1/Src/qtbase/src/plugins/sqldrivers/qtsqldrivers-config.pri: No such file or directory
Project ERROR: Library 'odbc' is not defined.

The absence of the qtsqldrivers-config.pri file can be ignored, but the second error will prevent us from building the plugin. To avoid it, you need to replace the line in the odbc.pro file:

#QMAKE_USE += odbc

After that, repeat the qmake call:

qmake "INCLUDEPATH+=/usr/local/unixODBC/include" "LIBS+=-L/usr/local/unixODBC/lib -lodbc"

And we get the Makefile output. Another issue that I encountered was the compiler flags -Wdate_time and -std = c ++ 1z, which caused a build error.

At this point, I already spent a lot of time to somehow build the plugin, so I solved this problem hard, just opened the generated Makefile and changed -std = c ++ 1z to -std = c ++ 11, and the flag -Wdate_time just deleted. These flag pairs are found in two places. You can install a more recent gcc, or can someone tell me if it is possible to specify some parameters for qmake to use c ++ 11 instead of c ++ 17?

No matter what you do, you can now do:

make
make install

The plugin is assembled.

Test application

I created a console application in Qt and wrote the following code to test the connection:

#include 
#include 
#include 
#include 
#include 
int main(int argc, char *argv[])
{
   QSqlDatabase db = QSqlDatabase::addDatabase("QODBC");
   QString connectionString = "DRIVER={ODBC Driver 13 for SQL Server};Server=\\,;Uid=;Pwd=";
   db.setDatabaseName(connectionString);
   if(db.open()) {
      std::cout << "Connection succes!" << endl;
      return 0;
   }else{
      std::cout << db.lastError().text().toStdString() << endl;
      return 1;
   }
}

We collect the project on the Virtualbox machine. We start, we are convinced that everything works. After that, we collect the Release version of the program. I will not now describe the deployment process of Qt applications. Perhaps this is a topic for another publication. I will describe only key points.

Along with the executable, you will need additional libraries that can be viewed using ldd. You will also need the plug-in that you have built. It lies in my case in QT_DIR / 5.9.1 / gcc_64 / plugins / sqldrivers and is called libsqlodbc.so. It must also be dragged away. You can put libraries for example in / usr / lib and the system will pick them up, but with plugins this is somewhat different. There are many ways to tell Qt where to load plugins. The simplest is to define the environment variable QT_PLUGIN_PATH before starting.

We start the program, everything should work.

Conclusion

I would like to hear comments on alternative solutions to this issue. I am pleased to supplement / correct this post.