Firebird select returns -2 result

[guidupas]

Hello!

I am facing a problem with a firebird SELECT. When I try to count the number of rows returned it returns the value -2

Does anyone know why?

bool queryRetornoDB::retornaValidadeUsuarioSistema()
{
    bool retorno;
    //retorno = true;
    retorno = false;
 
    QSqlQuery resultadoQuery;
 
    QString query = "SELECT * FROM usuario u";
 
    resultadoQuery.exec(query);
 
    int resultadoQueryNumLinhas = this->retornaQueryNumLinhas(resultadoQuery);
 
    qDebug() << "Valida usuário: ";
    qDebug() << resultadoQueryNumLinhas;
}

bool queryRetornoDB::retornaValidadeUsuarioSistema()
{
    bool retorno;
    //retorno = true;
    retorno = false;

    QSqlQuery resultadoQuery;

    QString query = "SELECT * FROM usuario u";

    resultadoQuery.exec(query);

    int resultadoQueryNumLinhas = this->retornaQueryNumLinhas(resultadoQuery);

    qDebug() << "Valida usuário: ";
    qDebug() << resultadoQueryNumLinhas;
}

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int queryRetornoDB::retornaQueryNumLinhas(QSqlQuery query)
{
    query.last();
    int linhas = query.at() + 1;
    return linhas;
}

int queryRetornoDB::retornaQueryNumLinhas(QSqlQuery query)
{
    query.last();
    int linhas = query.at() + 1;
    return linhas;
}

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Thanks

[Lesiok]

You must test values returned from QSqlQuery::exec and QSqlQuery::last.
-2 returned from QSqlQuery::last is QSql::AfterLastRow. This means that the resultset returned from QSqlQuery::exec is empty.

[ChrisW67]

If you want the number of rows then why not ask the database engine to tell you?
"Select count(*) from Usuario" and then retrieve the single row result.

[guidupas]

Thanks, it worked