[Qt-interest] Removing a database connection

[Jan]

Hi,

I know the error message "QSqlDatabasePrivate::removeDatabase: 
connection 'qt_sql_default_connection' is still in use, all queries will 
cease to work." has been discussed over and over.

But I still have a question: :-) I am struggling with closing a 
connection and renaming the sqlite file afterwards. Renaming the file is 
not possible if I get this error message. I think I found a solution 
(but I don't really understand why it works).

This produces the error message above:

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE");
db.setDatabaseName(qApp->applicationDirPath()+"/db.sqlite3");
db.close();
db = QSqlDatabase();
QSqlDatabase::database().removeDatabase(QSqlDatabase::defaultConnection);


... this not:

QSqlDatabase db = QSqlDatabase::addDatabase("QSQLITE", "default");
db.setDatabaseName(qApp->applicationDirPath()+"/db.sqlite3");
db.close();
db = QSqlDatabase();
QSqlDatabase::database().removeDatabase("default");

Why?