Hi everyone,

My small app has a button to start recording data into a database. A timer event happened every 1 second. My program write data to a database every second after the 'start' button has been clicked. A 'stop' button to stop recording data.

my problem is that after I click 'stop' button, and click 'start' again, i got a warning message from Qt creator:

"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."

I had a look the 'QSqlDatabase' class. the message indicates that a query on the database connection is still opened.

can anyone tell me how to stop the query in my program, please?
Thanks in advance.
here is part of my code:

Qt Code: 
  1. void cycleScrDialog::on_pushButton_clicked()
  2. {
  3.     // create new database
  4.     QDate sDate = QDate::currentDate();
  5.     QString dbName;
  6.     dbName = QString(QApplication::applicationDirPath()).append("/I-" + sDate.toString("MMyyyy") + ".db");
  7.     m4db = QSqlDatabase::addDatabase("QSQLITE");
  8.     m4db.setDatabaseName(dbName);
  9.  
  10.     if (!QFile::exists(dbName))
  11.     {
  12.         mydb.open();
  13.         QSqlQuery query;
  14.         query.exec("create table c1(ID int primary key unique, "
  15.                        "StartTime QString, StopTime QString)");
  16.         mydb.close();
  17.     }
  18.  
  19.     if (!mydb.open())
  20.     {
  21.         QMessageBox::warning(this, tr("Unable to open database"), tr("An error occurred while "
  22.                                       "opening the connection: ") + m4db.lastError().text());
  23.         return;
  24.     }
  25.     else
  26.     {
  27.         QSqlQuery query;
  28.         query.exec("PRAGMA synchronous = OFF");
  29.         model = new QSqlTableModel(this);
  30.         model->setEditStrategy(QSqlTableModel::OnManualSubmit);
  31.  
  32.         model->setTable("c1");
  33.         model->select();
  34.         model->insertRow(0);
  35.         model->setData(model->index(0, 1), String(qdatetime.toString(Qt::ISODate)));
  36.         model->setData(model->index(0, 2), String(qdatetime.toString(Qt::ISODate)));
  37.         model->submitAll();
  38.     }
  39.  
  40.     saveIni();
  41.     model->setTable("c1");
  42.     model->filter();
  43.     model->select();
  44. }
  45.  
  46. void cycleScrDialog::timer1000Event()
  47. {
  48.         model->setTable("c1");
  49.         model->select();
  50.         model->insertRow(0);
  51.         model->setData(model->index(0, 1), String(qdatetime.toString(Qt::ISODate)));
  52.         model->setData(model->index(0, 2), String(qdatetime.toString(Qt::ISODate)));
  53.         model->submitAll();
  54. }
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