ecto node migration

gistfile1.ex

defmodule Repo.Migrations.CreateNodes do
  use Ecto.Migration

  def up do
    [
      "CREATE TABLE IF NOT EXISTS nodes(id SERIAL PRIMARY KEY, name TEXT NOT NULL, script TEXT)",
      "CREATE TABLE IF NOT EXISTS node_to_node(parent_id INTEGER NOT NULL REFERENCES nodes(id) ON DELETE CASCADE, child_id INTEGER NOT NULL REFERENCES nodes(id) ON DELETE CASCADE)"
    ]
  end

  def down do
    [
      "DROP TABLE node_to_node",
      "DROP TABLE nodes"
    ]
  end
end