Invalid QSqlRecord after performing another query to DB

[crew4ok]

Hi everyone!

I have some problems with using QtSql.
So here's the code first:

QSqlQuery q1(db_connection), q2(db_connection);
q1.exec("SELECT * from users");
while(q1.next())
{
    q2.exec("delete from table1");
    if (!q2.isValid())
        qDebug() << "q2 is not valid";
 
    if (q1.isActive() && q1.isValid())
        qDebug() << q1.record();
}

QSqlQuery q1(db_connection), q2(db_connection);
q1.exec("SELECT * from users");
while(q1.next())
{
    q2.exec("delete from table1");
    if (!q2.isValid())
        qDebug() << "q2 is not valid";

    if (q1.isActive() && q1.isValid())
        qDebug() << q1.record();
}

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So there are two queries to one database: q1 is absolutely correct and should return several result rows, but q1 is some wrong query.
The question is why QSqlQuery::record() of q1 returns empty data after executing query q2?

I'm using MySQL 5.5.
I repeated this behaviour on qt 4.7.1 and qt 4.8.1 in Windows and Linux.

P.S.: Sorry for my english.