Not getting response from database

[Mikeeeeee]

Hi.
My program is connected to the Firebird database.
This query works in the Firebird database.

SELECT GEN_ID(GEN_UESRS_ID , 1) FROM RDB$DATABASE

But if I do so in Qt, the debug returns: query.value(0): 0

    query.prepare("SELECT GEN_ID(GEN_UESRS_ID , 1) FROM RDB$DATABASE");

    if(!query.exec())
    {
        emit sig_error(query.lastError().text());
        qDebug()<<"не записалось";
        qDebug()<<"query.lastError().text() : "<<query.lastError().text();
        msg = "false";
    }
    else {
        qDebug()<<"Ok";
        qDebug()<<"query.value(0):"<<query.value(0).toInt();
        msg = "true";
    }

Why am I not getting an answer and how do I fix it?

[VRonin]

change else { to else if(query.next()){