数据集排序问题

app/controllers/shixuns_controller.rb

@@ -459,7 +459,7 @@ class ShixunsController < ApplicationController
 	def get_data_sets
 		page = params[:page] || 1
 		limit = params[:limit] || 10
-		data_sets = @shixun.data_sets
+		data_sets = @shixun.data_sets.order("created_on desc")
 		@data_count = data_sets.count
 		@data_sets= data_sets.page(page).per(limit)
 		@absolute_folder = edu_setting('shixun_folder')