Copy tables between sqlite databases, qt, causes error

I want to write the contents of my sqlite database on user click to another sqlite database. For this I am trying to make connections to two databases and do select query from one db and in transaction do insert query to another. But I gets error on connection creation itself.

In header file:

private:
    QSqlDatabase database;
    QSqlDatabase mHistoryDB;

In source file:

    qDebug() << Q_FUNC_INFO << "Invoked";
    database = QSqlDatabase::addDatabase("QSQLITE");
    mHistoryDB = QSqlDatabase::addDatabase("QSQLITE");
#ifdef Q_OS_WIN
    database.setDatabaseName("C:/ANDROID_DATABASE/RestPos.sqlite");
    mHistoryDB.setDatabaseName("C:/ANDROID_DATABASE/History/RestPos.sqlite");
#else
    database.setDatabaseName("/mnt/sdcard/pos/RestPos.sqlite");
    mHistoryDB.setDatabaseName("/mnt/sdcard/pos/History/RestPos.sqlite");
#endif

While running I gets the following error:

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

QSqlDatabasePrivate::addDatabase: duplicate connection name 'qt_sql_default_connection', old connection removed.

If I use only database connection there occurs no error. I am not sure how to do copy with single connection.

My current copy code is as below:

bool readStatus     = false,
     writeStatus    = false;

if (database.isOpen() && mHistoryDB.open())
{
    QSqlQuery readQuery (database);
    QSqlQuery writeQuery(mHistoryDB);

    readStatus
            = readQuery.exec("SELECT costcentre_id, bill_no, bill_date "
                             "FROM BillHdr");
    qDebug() << Q_FUNC_INFO << getLastExecutedQuery(readQuery);

    if (readStatus)
    {
        mHistoryDB.transaction();
        writeQuery.prepare("INSERT INTO BillHdr "
                               "(costcentre_id, bill_no, bill_date) "
                           "VALUES (:costcentre_id, :bill_no, :bill_date)");

        while(readQuery.next())
        {
            if (readQuery.isValid())
            {
                BillHeader billHdr;
                billHdr.costCenterId = readQuery.value(0).toString();
                billHdr.billNumber   = readQuery.value(1).toDouble();
                billHdr.date         = readQuery.value(2).toDate();

                writeQuery.bindValue(":costcentre_id", billHdr.costCenterId);
                writeQuery.bindValue(":bill_no", billHdr.billNumber);
                writeQuery.bindValue(":bill_date", billHdr.date);

                writeStatus = writeQuery.exec();

                qDebug() << Q_FUNC_INFO << getLastExecutedQuery(writeQuery);

                if (!writeStatus)
                {
                    qDebug() << Q_FUNC_INFO << "error in write" <<
                                writeQuery.lastError().text();
                    mHistoryDB.rollback();
                    mHistoryDB.close();
                    break;
                }

            }
        }

        writeStatus = mHistoryDB.commit();
        qDebug() << Q_FUNC_INFO << "commit:" << writeStatus;

        if (!writeStatus)
        {
            mHistoryDB.rollback();
        }

        mHistoryDB.close();
    }
}

qDebug() << Q_FUNC_INFO << "Exits" << writeStatus;
return writeStatus;