I have two function, one is called at the start time, and the other is called whenever i want to create a new database.

Qt Code: 
  1. bool mainWindow::createConnection() 
  2. {
  3. 	db =  QSqlDatabase::addDatabase("QSQLITE");
  4. 	/* If the database do not exist
  5. 	I create one anew*/
  6. 	QFile check;
  7. 	check.setFileName(databaseName);
  8. 	QDir::setCurrent(QCoreApplication::applicationDirPath());
  9. 	#ifdef DEBUG
  10. 	qDebug()<<QCoreApplication::applicationDirPath();
  11. 	#endif
  12. 	db.setDatabaseName(databaseName);
  13. 	if (!check.exists()){
  14. 		QMessageBox::warning(0,QObject::tr("Database mancante"),"Sembra che il database precedente sia stato cancellato. Ne ho creato uno nuovo con lo stesso nome");
  15. 		#ifdef DEBUG
  16. 		qDebug()<<databaseName<<db.open();
  17. 		#endif
  18. 		createTable();
  19. 	}
  20. 	if (!db.open()) {	
  21. 		QMessageBox::warning(0,QObject::tr("Non riesco a connettermi al database"),"Controlla che un databse sia presente o scegline uno dal menu File");
  22. 	#ifdef DEBUG
  23. 	qDebug()<<db.lastError()<<db.open();
  24. 	#endif
  25. 		return false;
  26. }
  27. 		return true;
  28.  
  29. }
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Qt Code: 
  1. void mainWindow::newDB()
  2. {
  3. 	/* Creat un nuovo archivio*/
  4. 	if (db.isOpen())
  5. 	{
  6. 	removeConnection();
  7. 	#ifdef DEBUG
  8. 	qDebug()<<"newDB, closing conn.:"<<db.isOpen();
  9. 	#endif
  10. 	}
  11. 	QString fileName = QFileDialog::getSaveFileName(this, tr("Nuovo archivio"),QDir::homePath (),tr("Rubic (*.db)"));
  12. 	db =  QSqlDatabase::addDatabase("QSQLITE");
  13. 	db.setDatabaseName(fileName);
  14. 	#ifdef DEBUG
  15. 	qDebug()<<"newDB, creating"<<db.lastError()<<db.isOpen()<<fileName<<db.isValid();
  16. 	#endif
  17. 	if (db.isValid()){
  18. 	createTable();
  19. 	databaseName=fileName;
  20.  
  21. 	} 
  22.  
  23.  
  24. }
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But the debug says to me that, when I call newDB(), removeConnection() and db = QSqlDatabase::addDatabase("QSQLITE");, there is still in use the qt_sql_default connection.
The function removeConnection() is
Qt Code: 
  1. void mainWindow::removeConnection()
  2. {
  3. // 	db.close();
  4.  
  5. 	QSqlDatabase::removeDatabase(db.connectionName());
  6. }
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For this reason, I cannot start a new database.
Help appreciated.