mobilizon/priv/repo/migrations/20180110095317_create_members.exs

defmodule Eventos.Repo.Migrations.CreateMembers do
  use Ecto.Migration

  def change do
    create table(:members, primary_key: false) do
      add :role, :integer
      add :group_id, references(:groups, on_delete: :nothing)
      add :account_id, references(:accounts, on_delete: :nothing)

      timestamps()
    end

    create index(:members, [:group_id])
    create index(:members, [:account_id])

  end
end