AerolineaFrba.Compra.Form6.sePuedeEfectuarLaCompra C# (CSharp) Method

        private bool sePuedeEfectuarLaCompra()
        {
            Int64 nroTarjeta;
            Int64.TryParse(txtNroTarjeta.Text, out nroTarjeta);

            SqlDataReader reader;
            SqlCommand query = new SqlCommand();
            query.CommandType = CommandType.Text;
            query.CommandText = "SELECT * FROM [ABSTRACCIONX4].[TARJETAS] WHERE TARJ_NRO = " + nroTarjeta + "";
            query.Connection = Program.conexion();

            reader = query.ExecuteReader();
            reader.Read();

            if (reader.HasRows)
            {
                if (this.esTarjetaValida())
                {
                    tarjetaNueva = false;
                    esEfectivo = false;
                    return true;
                }
                else
                {
                    return false;
                }

            }

            if (cboFormaPago.Text.Equals("Tarjeta de crédito"))
            {
                tarjetaNueva = true;
            }else
            {
                tarjetaNueva = false;
                esEfectivo = true;
            }

            return true;
        }