gistfile2.txt

require 'dm-core'
require 'dm-migrations'
require 'dm-timestamps'
require 'dm-sweatshop'

DataMapper.setup(:default, "[insert_path_here]")

class Widget
  include DataMapper::Resource
  
  property :id, Serial
  property :nom, String
  timestamps :at
end

DataMapper.auto_migrate!

Widget.fixture{{
  :nom => /\w+/.gen,
  :created_at => (DateTime.send(:today))
}}

(0..50).each{ |i| Widget.gen(:created_at=>(DateTime.send(:today) - i)) }

joined_on_dates.sql

select * from widgets as t1 join widgets as t2 on 
(date(t1.created_at) < date(t2.created_at) and 
date(t2.created_at) <= (date(t1.created_at) + 10)) order by t2.id