Hi to all,
yes I've read the previous posts about it but nothing match my problem. I've compiled the MySQL driver following the Qt guide "SQL Database Drivers". Then I've checked the folder "C:\Qt\2010.02\qt\plugins\sqldrivers" in order to confirm the library installed:

Qt Code: 
  1. 10/02/2010  19.01             2.168 libqsqlite4.a
  2. 10/02/2010  19.01             2.178 libqsqlited4.a
  3. 10/03/2010  14.28             2.182 libqsqlmysql4.a
  4. 10/03/2010  14.28             2.192 libqsqlmysqld4.a
  5. 10/02/2010  19.01             2.178 libqsqlodbc4.a
  6. 10/02/2010  19.01             2.182 libqsqlodbcd4.a
  7. 10/02/2010  19.01           478.720 qsqlite4.dll
  8. 23/02/2010  09.44         1.728.157 qsqlited4.dll
  9. 10/03/2010  14.28           113.152 qsqlmysql4.dll
  10. 10/03/2010  14.28           942.617 qsqlmysqld4.dll
  11. 10/02/2010  19.01           154.624 qsqlodbc4.dll
  12. 10/02/2010  19.01           943.815 qsqlodbcd4.dll
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it seems to be ok!

So, I've tried to test a simple app subclassing a QWidget:

Qt Code: 
  1. #include <QSqlDatabase>
  2. #include <QDebug>
  3. #include "Widget.h"
  4. #include "ui_Widget.h"
  5.  
  6. Widget::Widget(QWidget *parent) :
  7.     QWidget(parent),
  8.     ui(new Ui::Widget)
  9. {
  10.     ui->setupUi(this);
  11.     QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
  12. }
  13.  
  14. Widget::~Widget()
  15. {
  16.     delete ui;
  17. }
  18.  
  19. void Widget::changeEvent(QEvent *e)
  20. {
  21.     QWidget::changeEvent(e);
  22.     switch (e->type()) {
  23.     case QEvent::LanguageChange:
  24.         ui->retranslateUi(this);
  25.         break;
  26.     default:
  27.         break;
  28.     }
  29. }
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but my "Application Output" has reported:

Qt Code: 
  1. Starting C:\Documents and Settings\D44\Desktop\testMySQL\debug\testMySQL.exe...
  2. QSqlDatabase: QMYSQL driver not loaded
  3. QSqlDatabase: available drivers: QSQLITE QODBC3 QODBC
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what is missing?

Thanks in advance