QSqlQuery not working

[BrainStorm]

int ProductsForm::categoryIdByName(const QString& name)
{
    QSqlQuery categories = QSqlQuery(model->database());
    categories.exec(QString("SELECT id FROM Categories WHERE name='%1'").arg(name));
    categories.first();
    return categories.value(0).toInt();

int ProductsForm::categoryIdByName(const QString& name)
{
    QSqlQuery categories = QSqlQuery(model->database());
    categories.exec(QString("SELECT id FROM Categories WHERE name='%1'").arg(name));
    categories.first();
    return categories.value(0).toInt();

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it works now, and i still don't know why! ^^" but thanks anyway