mobilizon/priv/repo/migrations/20180515100237_create_comments.exs

defmodule Mobilizon.Repo.Migrations.CreateComments do
  use Ecto.Migration

  def change do
    create table(:comments) do
      add :url, :string
      add :text, :text

      add :account_id, references(:accounts, on_delete: :nothing), null: false
      add :event_id, references(:events, on_delete: :nothing)
      add :in_reply_to_comment_id, references(:categories, on_delete: :nothing)
      add :origin_comment_id, references(:addresses, on_delete: :delete_all)

      timestamps()
    end
  end
end