mysql is installed but can not load

[vanduongbk]

hi everyone,i have install mysql on window with vs2008 complete
but when i test a code as belows,it can not load ,plz help
this is a test code:

#include <QCoreApplication>
#include <QtSql>
#include <QDebug>
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QSqlDatabase db=QSqlDatabase::addDatabase("qmysql","db");
    db.setHostName("testmysql");
    db.setDatabaseName("testdb");
    db.setUserName("vanduongbk");
    db.setPassword("sa123");
    if(!db.open())
    {
        qDebug()<<"error connect"<<db.lastError().text();
    }
    else
    {
        qDebug()<<"connected";
    }
    //MainWindow w;
   // w.show();
 
    return a.exec();
}

#include <QCoreApplication>
#include <QtSql>
#include <QDebug>

int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
    QSqlDatabase db=QSqlDatabase::addDatabase("qmysql","db");
    db.setHostName("testmysql");
    db.setDatabaseName("testdb");
    db.setUserName("vanduongbk");
    db.setPassword("sa123");
    if(!db.open())
    {
        qDebug()<<"error connect"<<db.lastError().text();
    }
    else
    {
        qDebug()<<"connected";
    }
    //MainWindow w;
   // w.show();

    return a.exec();
}

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when compile,it have error as :
Starting C:\Documents and Settings\vanduongbk\My Documents\myqtproject\build-mysqlproject1-Desktop-Debug\debug\mysqlproject1...
QSqlDatabase: qmysql driver not loaded
QSqlDatabase: available drivers: QSQLITE QMYSQL3 QMYSQL QODBC3 QODBC QPSQL7 QPSQL
error connect "Driver not loaded Driver not loaded"