turnerking

class Job < ActiveRecord::Base
  has_many :requirements
  has_many :required_jobs, :source => :derived_job, :through => :requirements
  has_many :derived_jobs, :source => :required_job, :through => :requirements
end

class Requirement < ActiveRecord::Base
  belongs_to :derived_job, :class_name => "Job"
  belongs_to :required_job, :class_name => "Job"
end

turnerking

SELECT SQL_CALC_FOUND_ROWS o.*, 
  (CASE TRUNCATE((
      SELECT (SUM(oi.case_or_pack)/COUNT(*)) 
      FROM order_items as oi, orders as o 
      WHERE o.order_id = oi.order_id)
      ,2)  
    WHEN 2.00 
      THEN "CA" 
    WHEN 1.00 
      THEN "EA"