关于QSqlQuery的问题 [复制链接]

    QString username;
    QString password;
    QStringList list=msg.split(" ");
    username=list.at(0);
    password=list.at(1);
    QSqlDatabase db = QSqlDatabase::addDatabase("QMYSQL");
    db.setHostName("localhost");
    db.setDatabaseName("test");
    db.setUserName("****8888");
    db.setPassword("***88888");
    if (!db.open()) {
        QMessageBox::critical(0, qApp->tr("Cannot open database"),
            qApp->tr("Unable to establish a database connection.\n"
                     "This example needs MySQL support. Please read "
                     "the Qt SQL driver documentation for information how "
                     "to build it.\n\n"
                     "Click Cancel to exit."), QMessageBox::Cancel);
    }
    QSqlQuery query=QSqlQuery(db);
    query.prepare("select password from test.usertable where username= ?");
    query.addBindValue(username);
    query.exec();
    while(query.next())
   {
        if( password == query.value(0).toString() )
             emit updateServer(msg,length);
   }

上面代码的emit updateServer(msg,length); 总是无法执行
请教高手指点！！！
谢谢

我试过改为：
    query.prepare("select id from test.usertable where username= ? and password= ? ");
        query.addBindValue(username);
        query.addBindValue(password);
         query.exec();
         while(query.next())
         {
             emit updateServer(msg,length);
        }
也是无法执行 emit 代码？？？

在emit 之前qDebug()一下，看看到底有没有到达该位置。

        qDebug("+++++++++++++++++++++++++++++++");
        if( password == query.value(0).toString() )
        {
            qDebug("=======================");
            emit updateServer(msg,length);
        }
程序可以输出+++++++++++
但没有输出=============

引用第1楼caichao07于2010-02-23 20:32发表的  :
我试过改为：
    query.prepare("select id from test.usertable where username= ? and password= ? ");
        query.addBindValue(username);
        query.addBindValue(password);
         query.exec();
.......

query没有查询出记录来~~~~

我用qDebug()查出来了，原来比较的数据和数据库里的数据不一致，谢谢指教！！！