C#

private void updateIndex(int id)
{
    string update = "UPDATE questions SET indexrow=@idintrebare WHERE id=@idintrebare;";
    using (var connection = Conexiune.getConnection())
    using (SQLiteCommand cmd = new SQLiteCommand(update, connection))
    {
        connection.Open();
        cmd.Parameters.AddWithValue("@idintrebare", id);
        cmd.ExecuteNonQuery();
    }
}

string update = "UPDATE questions SET indexrow=@idintrebare WHERE id=@idintrebare;";
            using (var connection = Conexiune.getConnection())
            using (SQLiteCommand cmd = new SQLiteCommand(update, connection))
            {
                connection.Open();
                cmd.Parameters.AddWithValue("@idintrebare", idintrebare);
                cmd.ExecuteNonQuery();
            }

private static string conn = @"Data Source=database.db;Pooling=true;FailIfMissing=false;Version=3;";
        public static SQLiteConnection connect = null;
        private Conexiune() { }
        public static SQLiteConnection getConnection()
        {
            SQLiteConnection connect = null;
            try
            {
                connect = new SQLiteConnection(conn);
                connect.Open();
                return connect;
            }
            catch (SQLiteException e)
            {
                throw new Exception("Cannot connect", e);
            }
        }

string selectareLicenta = "SELECT licenta FROM licente WHERE licenta = '" + maskedTextBox1.Text + "'";
            using (SQLiteCommand cmd = new SQLiteCommand(selectareLicenta, Conexiune.getConnection()))
            {
                using (SQLiteDataReader read = cmd.ExecuteReader(CommandBehavior.CloseConnection))
                {
                    if (read.Read())
                    {
                        SimulatorManager.Licenta = read["licenta"].ToString();
                    }
                    read.Close();
                }
            }

string selectareLicenta = "SELECT licenta FROM licente WHERE licenta = '" + maskedTextBox1.Text + "'";
using (SQLiteConnection conn = Conexiune.getConnection())
using (SQLiteCommand cmd = new SQLiteCommand(selectareLicenta, conn))
using (SQLiteDataReader read = cmd.ExecuteReader(CommandBehavior.CloseConnection))
{
    if (read.Read())
    {
        SimulatorManager.Licenta = read["licenta"].ToString();
    }
    // no need to explicitly close the reader when used in a using-block
}

string selectutilizator = "SELECT * FROM accounts";
            using (SQLiteCommand selcom = new SQLiteCommand(selectutilizator, Conexiune.getConnection()))
            {
                using (SQLiteDataReader read = selcom.ExecuteReader())
                {
                    if (read.HasRows)
                    {
                        Application.Run(new Elev());
                    }
                    else Application.Run(new Intro());
                }
            }

string selectutilizator = "SELECT * FROM accounts";
            bool hasrows=false;
            using (SQLiteCommand selcom = new SQLiteCommand(selectutilizator, Conexiune.getConnection()))
            {
                using (SQLiteDataReader read = selcom.ExecuteReader())
                {
                    if (read.HasRows)
                    {
                        hasrows=true;
                    }
                }
            }
            if (hasrows) Application.Run(new Elev());
            else Application.Run(new Intro());

DPaul1994 wrote:

Yes, you right. Thank you very much!

private void updateIndex()
{
    const string update = "UPDATE questions SET indexrow = @idintrebare WHERE id = @idintrebare";
    using (SQLiteCommand comp = new SQLiteCommand(update, Conexiune.getConnection()))
    {
        comp.CommandType = CommandType.Text;
        comp.Parameters.AddWithValue("@idintrebare", idintrebare);
        comp.ExecuteNonQuery();
    }
}

The ... constructor (which is like an instance method) ...
Because the constructor is an instance member, it is permitted to access both the ... instance field and the ... static field.

Unlike other members, instance constructors are not inherited, and a class has no instance constructors other than those actually declared in the class. If no instance constructor is supplied for a class, then an empty one with no parameters is automatically provided.

If an instance constructor has no constructor initializer, a constructor initializer of the form base() is implicitly provided. Thus, an instance constructor declaration of the form
     C(...) {...}
is exactly equivalent to
     C(...): base() {...}