Ecto.ex

defmodule Image do
  @moduledoc false
  use Ecto.Model

  @primary_key {:Id, :binary_id, autogenerate: false}
  schema "Images" do
    field :name
    field :extension
    field :path
  end
end

defmodule Section do
  @moduledoc false
  use Ecto.Model

  @primary_key {:id, :binary_id, autogenerate: false}
  schema "Sections" do
    field :name
    field :number, :integer
    field :systemonly, :boolean
    has_many :image_sections, ImageSection, foreign_key: :sectionid
  end
end

defmodule ImageSection do
  @moduledoc false
  use Ecto.Model

  @primary_key false
  schema "ImageSections" do
    field :imageid, :binary_id, primary_key: true
    field :sectionid, :binary_id, primary_key: true
    field :Previousimageid, :binary_id
    has_one :image, Image, references: :imageid, foreign_key: :id
  end
end

def query5 do
  query = from i in Section,
  select: i, limit: 100, preload: :image_sections
  Repo.all(query)
end