public class Termek { public int Id { get; set; } public string Nev { get; set; } public decimal Ar { get; set; } }

private readonly List<Termek> lista = new List<Termek>
{
    new Termek { Id = 1, Nev = "Alma", Ar = 120.5m },
    new Termek { Id = 2, Nev = "Körte, érett", Ar = 200m }   // a vessző a CsvHelper idézi: nem rontja el a CSV-t
};

private void Form1_Load(object sender, EventArgs e)
{
    foreach (var a in AppDomain.CurrentDomain.GetAssemblies().OrderBy(x => x.GetName().Name))
    {
        lstBetoltott.Items.Add(a.GetName().Name + " " + a.GetName().Version);
    }
}

private void btnExport_Click(object sender, EventArgs e)
{
    string ut = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments), "termekek.csv");

    try
    {
        using (StreamWriter w = new StreamWriter(ut, false, new System.Text.UTF8Encoding(true)))
        using (CsvWriter csv = new CsvWriter(w, CultureInfo.InvariantCulture))
        {
            csv.WriteRecords(lista);
        }

        lblUzenet.Text = "CSV mentve: " + ut;
    }
    catch (Exception ex) when (ex is IOException || ex is UnauthorizedAccessException) { lblUzenet.Text = "A mentés nem sikerült: " + ex.Message; }
}

private void btnDb_Click(object sender, EventArgs e)
{
    string db = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ApplicationData), "Audit", "termekek.db");

    try
    {
        Directory.CreateDirectory(Path.GetDirectoryName(db));

        using (SqliteConnection kap = new SqliteConnection("Data Source=" + db))
        {
            kap.Open();

            using (SqliteCommand c = kap.CreateCommand())
            {
                c.CommandText = "CREATE TABLE IF NOT EXISTS termek (id INTEGER PRIMARY KEY, nev TEXT, ar REAL)";
                c.ExecuteNonQuery();
            }

            foreach (Termek t in lista)
            {
                using (SqliteCommand c = kap.CreateCommand())
                {
                    c.CommandText = "INSERT OR REPLACE INTO termek (id, nev, ar) VALUES ($i, $n, $a)";
                    c.Parameters.AddWithValue("$i", t.Id);
                    c.Parameters.AddWithValue("$n", t.Nev);
                    c.Parameters.AddWithValue("$a", (double)t.Ar);
                    c.ExecuteNonQuery();
                }
            }
        }

        lblUzenet.Text = "Adatbázis mentve: " + db;
    }
    catch (SqliteException ex) { lblUzenet.Text = "Adatbázis-hiba: " + ex.Message; }
    catch (Exception ex) when (ex is IOException || ex is UnauthorizedAccessException) { lblUzenet.Text = "Fájlhiba: " + ex.Message; }
}