segfault

try 	{ 		query = new QSqlQuery(m_db); 		}  	catch ( exception & e ) 	{ 		QString temp = e.what();  		msgBox.setStandardButtons(QMessageBox::Cancel);		msgBox.setIcon(QMessageBox::Critical);		msgBox.setText(temp);		msgBox.exec();	}		if(m_db.open())	{		query->exec("SELECT * FROM ARTICLE_DE_BLOG");		QString temp = query->value(0).toString();		msgBox.setText(qApp->tr("hi"));		msgBox.exec();		this->m_open = true ;	}