Qt连接MySQL出错Driver not loaded

    QSqlDatabase mysqldb=QSqlDatabase::addDatabase("QMYSQL");
    mysqldb.setHostName(QObject::tr("10.0.1.209"));
    mysqldb.setDatabaseName(QObject::tr("skystore"));
    mysqldb.setUserName(QObject::tr("skystore"));
    mysqldb.setPassword(QObject::tr("8888"));
    if(!mysqldb.open())
    {
        QMessageBox::critical(0,QObject::tr("DataBase Error!"),mysqldb.lastError().text());

    }else{
        QMessageBox::critical(0,QObject::tr("DataBase OK!"),QObject::tr("DataBase OK!"));
    }