Sometimes we need to display the records in a specific order. For that, we need some method
Suppose I have the priorities ['0', '8', '4'] .And I have a model event with priority column.

Now I need to get all the events order by priority. Here priorities are not following any order(DESC, ASC).

So below code would work.
Event.all(:order => "priority DESC")
So we can do one thing, we can create a scope.
then you will probably want to use a default_scope.

For example:

class Event < ActiveRecord::Base
scope :by_priority, :order => order_by_case

EVENT_ORDERED = ['0', '8', '4']

  def self.order_by_case
    ret = "CASE"
    EVENT_ORDERED.each_with_index do |p, i|
      ret << " WHEN reviewer_relationships = '#{p}' THEN #{i}"
    end
    ret << " END DESC"
  end

end

And then invoke the scope by something like this:

@events=  Event.all.by_priority