MySQL Ecto returning

mysql.ex

defmodule MySQL do
  defmacro __using__(_opts \\ []) do
    quote do
      defoverridable insert_all: 3

      def insert_all(schema_or_source, entries, opts) when is_list(entries) do
        {returning, opts} = Keyword.pop(opts, :returning)

        if returning do
          import Ecto.Query

          {:ok, return} =
            transaction(fn ->
              super(schema_or_source, entries, opts)

              inserts =
                all(
                  from p in schema_or_source,
                    where: p.id >= fragment("LAST_INSERT_ID()"),
                    where: p.id <= fragment("LAST_INSERT_ID()") + (fragment("ROW_COUNT()") - 1)
                )

              {length(inserts), inserts}
            end)

          return
        else
          super(schema_or_source, entries, opts)
        end
      end
    end
  end
end