I am currently using an MSSQL database through tds_ecto.
Since tds_ecto currently works with ecto 2 I made the following changes to mix.exs

  def application do
    [
      mod: {Hello.Application, []},
      extra_applications: [:logger, :runtime_tools, :tds_ecto, :ecto]
    ]
  end

  defp deps do
    [
      {:phoenix, "~> 1.4.0"},
      {:phoenix_pubsub, "~> 1.1"},
      {:phoenix_ecto, "~> 3.0"},
      {:ecto, "~> 2.2"},
      {:tds_ecto, "~> 2.2"},
      {:phoenix_html, "~> 2.11"},
      {:phoenix_live_reload, "~> 1.2", only: :dev},
      {:gettext, "~> 0.11"},
      {:jason, "~> 1.0"},
      {:plug_cowboy, "~> 2.0"}
    ]
  end

Does Phoenix 1.4 work with Ecto 2?

Should I revert to Phoenix 1.3?