Hi all,

In my program i have a main class (kentrko) which creates a QSqlDatabase* object. I want to pass this object to a dialogue to detect whether the connection is opened or closed and if not to open it. The code works fine and compiles but i receive the following error when I am opening the dialogue window again:
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.
kentriko class:
Qt Code: 
  1. #include "kentriko.h"
  2. #include <QMdiSubWindow>
  3.  
  4. kentriko::kentriko(QWidget *parent)
  5.     : QMainWindow(parent)
  6. {
  7. 	ui.setupUi(this);
  8. 	connect(ui.actionAnalisi, SIGNAL(triggered()), this, SLOT(anixe_analisi()));
  9. 	connect(ui.actionSindesi, SIGNAL(triggered()), this, SLOT(anixe_sindesi()));
  10. 	*db = QSqlDatabase::addDatabase("QMYSQL");
  11. }
  12.  
  13. void kentriko::anixe_sindesi(){
  14. sindesi *sindesi1= new sindesi(0,db) ;
  15. sindesi1->show();
  16. }
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and the kentriko header:
Qt Code: 
  1. #ifndef KENTRIKO_H
  2. #define KENTRIKO_H
  3. #include <QtGui/QMainWindow>
  4. #include "ui_kentriko.h"
  5. #include <QtSql>
  6. #include "../parathrira/sindesi/sindesi.h"// i klasi silogi ine orismeni apo tin sindesi giayto xreazete edo to header
  7. #include "../parathrira/analisi/analisi.h"
  8. class kentriko : public QMainWindow
  9. {
  10.     Q_OBJECT
  11. public:
  12.     kentriko(QWidget *parent = 0);
  13.     ~kentriko();
  15.  public slots:
  16.    void anixe_analisi ();
  17.    void anixe_sindesi ();
  18. };
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the dialog that i want to pass the db and manipulate it is:

Qt Code: 
  1. #ifndef SINDESI_H
  2. #define SINDESI_H
  3. #include <QtSql>
  4. #include <QtGui/QDialog>
  5. #include "ui_sindesi.h"
  6.  
  7. class sindesi : public QDialog
  8. {
  9.     Q_OBJECT
  10.  
  11. public:
  12.     sindesi(QWidget *parent , QSqlDatabase* db);
  13.     ~sindesi();
  15. public slots:
  16.   void sindesou();
  17.   void aposindesou();
  18.  
  19. private:
  20.     Ui::sindesiClass ui;
  21. };
  22.  
  23. #endif // SINDESI_H
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and the implementation:
Qt Code: 
  1. #include "sindesi.h"
  2. #include <QtSql>
  3. sindesi::sindesi(QWidget *parent,QSqlDatabase* db)
  4.     : QDialog(parent)
  5. {
  6. db3=db;
  7. 	ui.setupUi(this);
  8. 	connect(ui.sindesi, SIGNAL(clicked()), this, SLOT(sindesou()));
  9. 	connect(ui.aposindesi, SIGNAL(clicked()), this, SLOT(aposindesou()));
  10. }
  11. void sindesi::sindesou() {
  12.   if (db3->isOpen())
  13.     ui.pliroforia_2->setText("ine idi anixti");
  14. if (!db3->isOpen()) {
  15.         db3->setDatabaseName(ui.pinakas->text());
  16.         db3->setUserName(ui.onoma->text());
  17.         db3->setPassword(ui.kodikos->text());
  18.         db3->setHostName("127.0.0.1");
  19.         db3->setPort(3306);
  20.         if (!db3->open()) {
  21.             ui.katastasi->setText("Not connected");
  22.         } else {
  23.             ui.katastasi->setText("connected");
  24.         }
  25. } else {
  26.         ui.katastasi->setText("It has already been connected");
  27.     }
  28. }
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Any ideas why is this happening?

Many thanks in advance.