QSqlDatabasePrivate::removeDatabase: connection 'myConnectionName' is still in use, all queries will cease to work.

[Taz742]

I have a folder where i have a many databases. Some times may be deleted or added database to the folder.
So I use QTimer and read all databases.

It is a my code:

this->timer = new QTimer(this);
this->timer->setInterval(15000);
connect(this->timer, &QTimer::timeout, this, [=]() {
    QString path = "C:\\Users\\User\\Desktop\\DAXI SMS SENDER\\SMSSenderAllBASE";
    //QString path = qApp->applicationDirPath() + "\\SMSSenderAllBASE";
    QDir recoredDir(path);
    QStringList allFiles = recoredDir.entryList(QDir::NoDotAndDotDot | QDir::System | QDir::Hidden  | QDir::AllDirs | QDir::Files, QDir::DirsFirst);
    for (int i = 0; i < allFiles.size(); i++) {
        QString fullPath = path + "\\" + allFiles[i];
        QString connectionName = allFiles[i];
        connectionName = connectionName.remove(connectionName.size() - 4, 4);
        QSqlDatabase db = QSqlDatabase::addDatabase("QIBASE", connectionName);
        db.setDatabaseName(fullPath);
        db.setHostName("localhost");
        db.setPort(3050);
        db.setUserName("SYSDBA");
        db.setPassword("masterkey");

        thrdHelperSendSMS *help = new thrdHelperSendSMS(db, this);
        connect(help, &thrdHelperSendSMS::helperFinished, this, [=](QString connectionName){
            QSqlDatabase t_db = QSqlDatabase::database(connectionName);
            t_db.close();
            QSqlDatabase::removeDatabase(connectionName);
            delete help;
        });
        help->run();
    }
});
this->timer->start();

Yes I'm sure that the helperFinished signal will happen and this time I will not have any connection with this base.

EDIT:
If i remove

   thrdHelperSendSMS *help = new thrdHelperSendSMS(db, this);
   connect(help, &thrdHelperSendSMS::helperFinished, this, [=](QString connectionName){
       QSqlDatabase t_db = QSqlDatabase::database(connectionName);
       t_db.close();
       QSqlDatabase::removeDatabase(connectionName);
       delete help;
   });
   help->run();

example:

for (int i = 0; i < allFiles.size(); i++) {
    QString fullPath = path + "\\" + allFiles[i];
    QString connectionName = allFiles[i];
    connectionName = connectionName.remove(connectionName.size() - 4, 4);
    QSqlDatabase db = QSqlDatabase::addDatabase("QIBASE", connectionName);
    db.setDatabaseName(fullPath);
    db.setHostName("localhost");
    db.setPort(3050);
    db.setUserName("SYSDBA");
    db.setPassword("masterkey");

    QSqlDatabase::removeDatabase(connectionName);
}

I have the same error.

[Taz742]

@SGaist
Yes i using it wrong.

Wrong use

QSqlDatabase db = QSqlDatabase::database("sales");
QSqlQuery query("SELECT NAME, DOB FROM EMPLOYEES", db);
QSqlDatabase::removeDatabase("sales"); // will output a warning

Correct use

{
    QSqlDatabase db = QSqlDatabase::database("sales");
    QSqlQuery query("SELECT NAME, DOB FROM EMPLOYEES", db);
}
// Both "db" and "query" are destroyed because they are out of scope
QSqlDatabase::removeDatabase("sales"); // correct

[SGaist]

Hi,

Take a look at the removeDatabase documentation for an example of how to implement it properly.

[Taz742]

@SGaist
Yes i using it wrong.

Wrong use

QSqlDatabase db = QSqlDatabase::database("sales");
QSqlQuery query("SELECT NAME, DOB FROM EMPLOYEES", db);
QSqlDatabase::removeDatabase("sales"); // will output a warning

Correct use

{
    QSqlDatabase db = QSqlDatabase::database("sales");
    QSqlQuery query("SELECT NAME, DOB FROM EMPLOYEES", db);
}
// Both "db" and "query" are destroyed because they are out of scope
QSqlDatabase::removeDatabase("sales"); // correct