Problem with MySQL

[sali555]

hi guys,

I have problem with the connection to MySQL. I have created a database on localhost and iI connected to it, but the data doesn't show. I can see only empty lines like in attachment I use class QSqlRelationalTableModel.

Here is my code:

QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("pokus");
    db.setUserName("root");
    db.setPassword("password");
    if (!db.open())
    {
      QMessageBox::warning(this, tr("Connection Error"), tr("Cannot open DB file"));
      return;
    }
 
    m_mainModel = new QSqlRelationalTableModel(this);
    m_mainModel->setEditStrategy(QSqlTableModel::OnManualSubmit);
 
    ui->tableView->setModel(m_mainModel);
 
    m_mainModel->setTable("SPORTOVEC");
    if (!m_mainModel->select())
    {
            QMessageBox::warning(this, tr("Select Error"), m_mainModel->lastError().databaseText());
            return;
    }

QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("pokus");
    db.setUserName("root");
    db.setPassword("password");
    if (!db.open())
    {
      QMessageBox::warning(this, tr("Connection Error"), tr("Cannot open DB file"));
      return;
    }

    m_mainModel = new QSqlRelationalTableModel(this);
    m_mainModel->setEditStrategy(QSqlTableModel::OnManualSubmit);

    ui->tableView->setModel(m_mainModel);

    m_mainModel->setTable("SPORTOVEC");
    if (!m_mainModel->select())
    {
            QMessageBox::warning(this, tr("Select Error"), m_mainModel->lastError().databaseText());
            return;
    }

To copy to clipboard, switch view to plain text mode 

sorry about my English.
please help

[d_stranz]

It looks like you aren't specifying any filter or sort condition, so the "select()" statement is doing exactly what you've told it to do: select nothing.

Look at the documentation for QSqlTableModel::select() and ::setFilter(). Try using setFilter( "*" ) and see what you get.

[unit]

try ui->tableView->setModel(m_mainModel); after !m_mainModel->select()

[d_stranz]

try ui->tableView->setModel(m_mainModel); after !m_mainModel->select()

This doesn't matter, and it really is the wrong order to do things. If the model and table view are working together (as the Model/View archtecture says they should) then every time there is a new select(), the table view will automatically be updated because the model will emit a modelReset() or dataChanged() signal. It isn't necessary to tell the table about the model each time you do a select.

[unit]

This doesn't matter, and it really is the wrong order to do things. If the model and table view are working together (as the Model/View archtecture says they should) then every time there is a new select(), the table view will automatically be updated because the model will emit a modelReset() or dataChanged() signal. It isn't necessary to tell the table about the model each time you do a select.

Dear d_stranz. I'm not developer, but like read source code. And i known that you are good QT developer.
But try my example and sali555

if (!db.open())
    {
      QMessageBox::warning(this, tr("Connection Error"), tr("Cannot open DB"));
      return;
    }
 
    m_mainModel = new QSqlRelationalTableModel(this, db);
    m_mainModel->setEditStrategy(QSqlTableModel::OnManualSubmit);
 
    m_mainModel->setTable("SPORTOVEC");
    if (!m_mainModel->select())
    {
            QMessageBox::warning(this, tr("Select Error"), m_mainModel->lastError().databaseText());
            return;
    }
 
    ui->tableView->setModel(m_mainModel);

if (!db.open())
    {
      QMessageBox::warning(this, tr("Connection Error"), tr("Cannot open DB"));
      return;
    }

    m_mainModel = new QSqlRelationalTableModel(this, db);
    m_mainModel->setEditStrategy(QSqlTableModel::OnManualSubmit);

    m_mainModel->setTable("SPORTOVEC");
    if (!m_mainModel->select())
    {
            QMessageBox::warning(this, tr("Select Error"), m_mainModel->lastError().databaseText());
            return;
    }

    ui->tableView->setModel(m_mainModel);

To copy to clipboard, switch view to plain text mode 

It's work as sali555 want. Yes, ofcouse. We can use sort filter and other for prepare view column, and then use select statement, but is more easy way use select and then link model with view. In this way view automatically assign all column.

So you should have not empty model to prepare your view.

And sorry my English plz.

[sali555]

unit: you are right. it works perfect. thanks.

Now I have a problem with a select query. I have a list of people( men and women) and now I would like to show only the rows with women. How can I do this?

I know how I can do it with object QSqlQueryModel but I don't know how can I do this with QSqlRelationTableModel. Any Ideas?

[d_stranz]

You can either change your select statement to only select entries "where sex='F'" or you can add a QSortFilterProxyModel that will return false for "filterAcceptsRow() for any row where the sex is male. It is probably easier and more flexible just to change your select statement.

[unit]

use setFilter ( const QString & filter )
Sets the current filter to filter.
The filter is a SQL WHERE clause without the keyword WHERE (for example, name='Josephine').
If the model is already populated with data from a database, the model re-selects it with the new filter. Otherwise, the filter will be applied the next time select() is called.

it's like m_mainModel->setFilter("sex=1"); or m_mainModel->setFilter("sex=\'F\'");

[sali555]

yeah, setFilter() works fine. thanks