ecto query examples

ecto-query.ex

# Query with preload and join

```elixir
q = from l in List,
          join: ul in UserList,
          where: ul.user_id == ^current_user.id and l.id == ul.list_id,
          order_by: [desc: l.done_at, asc: l.id]
    lists = q |> preload(:user) |> Repo.all
    
```