// mainwindows.h

public:
QSqlDatabase mydb;
void connClose()
{
    connected = false;
    mydb.close();
    mydb.QSqlDatabase();
    mydb.removeDatabase(QSqlDatabase::defaultConnection);
}

bool connOpen()
{
    if( !connected )
    {
        mydb = QSqlDatabase::addDatabase("QODBC"); //uses dsn, connects fine.
        mydb.setDatabaseName("Test");
        if(!mydb.open())
        {
            qDebug() << mydb.lastError().text();
            connected = false;
        }
        else
        {
            qDebug()<<"Connected";
            connected = true;
        }
    }
    return connected;
}

private:
static bool connected;

Financelog::Financelog(QWidget *parent) :
QDialog(parent),
ui(new Ui::Financelog)
{
    ui->setupUi(this);
    setWindowFlags( windowFlags() | Qt::WindowMinimizeButtonHint |
                    Qt::WindowContextHelpButtonHint | Qt::WindowMinMaxButtonsHint );

    MainWindow conn; // call the connection string
    if(!conn.connOpen())
        ui->label_sec_status->setText("<font color='red'>Failed to Open Database</font>");
    else
        ui->label_sec_status->setText("<font color='green'>Connected</font>");

    QSqlQueryModel * modal=new QSqlQueryModel();

    conn.connOpen(); // ---- **DO I NEED THIS? REMOVING STOPS CRASHES.**

    QSqlQuery* qry=new QSqlQuery(conn.mydb);

    qry->prepare("select DEAL_DATE, DEAL_NUMB, CCICOMM, CCIPREM, INCOME from LOG");
    qry->exec();
    modal->setQuery(*qry);
    ui->tableView->setModel(modal);
    ui->tableView->resizeColumnsToContents();
    ui->tableView->setAlternatingRowColors(true);
    ui->tableView->setStyleSheet("alternate-background-color: #009900; background-color: #006600;");

    //delete qry;  **DO I NEED THIS TO RELEASE MEMORY?**

    conn.connClose(); // **DO I NEED THIS?**

    qDebug() << (modal->rowCount());
}

//only once, i.e. in your windows constructor
conn.connOpen();

//set up the model
QSqlQueryModel * modal=new QSqlQueryModel();

QSqlQuery qry(conn.mydb);

qry.prepare("...");
qry.exec();
modal->setQuery(qry);
//...

// do not delete the query or close the database connection!

qDebug() << (modal->rowCount());

model->deleteLater();
conn.connClose();