(Another) segmentation fault

[Lebowski]

Following that example I changed

1.
      void GlavnoO :: pushButton3_clicked()
      {
          bool ok = FALSE;
          ok = povezava.baza->isOpen();
      }

1.
      void GlavnoO :: pushButton3_clicked()
      {
          bool ok = FALSE;
          ok = povezava.baza->isOpen();
      }

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to

void GlavnoO::pushButton3_clicked()
{
    bool ok = FALSE;
    QSqlDatabase *baza = QSqlDatabase::database();
    ok = baza->isOpen();
}

void GlavnoO::pushButton3_clicked()
{
    bool ok = FALSE;
    QSqlDatabase *baza = QSqlDatabase::database();
    ok = baza->isOpen();
}

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It compiles normally but it crashes with segmentation fault again when I press that button.

And I have to use pointers cause I have this in my Qt Assistant QSqlDatabase Reference:

Static Public Members
QSqlDatabase * addDatabase ( const QString & type, const QString & connectionName = defaultConnection )
QSqlDatabase * addDatabase ( QSqlDriver * driver, const QString & connectionName = defaultConnection )
QSqlDatabase * database ( const QString & connectionName = defaultConnection, bool open = TRUE )
void removeDatabase ( const QString & connectionName )
void removeDatabase ( QSqlDatabase * db )
bool contains ( const QString & connectionName = defaultConnection )
QStringList drivers ()
void registerSqlDriver ( const QString & name, const QSqlDriverCreatorBase * creator )
bool isDriverAvailable ( const QString & name )