db application c++

Hello.
I have experience in php and c++ , and I have to choose the language and the database right for my application.
I wish that my application was accessible over the network from 3 different pc.
I wish that on my PC was installed the relational db (mysql or Postrgres or SqlLite) and that this was accessible to the 3 PC.

Now, if I use php is very easy to share the application with apache and mysql.
the problem is that I would like to experience the QT c in a db and I would like to share my application and the db with PCs connected to the network.
just change the connection string to the db on the different pc or is it more complicated?
db that you recommend?

thanks.