修改管理员界面作业列表的截止时间为作业发布时间，并且按时间倒序排列

app/controllers/admin_controller.rb

@@ -548,7 +548,8 @@ class AdminController < ApplicationController
 
   #作业
   def homework
-    @homework = HomeworkCommon.order('end_time desc')
+    #@homework = HomeworkCommon.order('end_time desc')
+    @homework = HomeworkCommon.order( 'created_at desc ')
     @homework = paginateHelper @homework,30
     @page = (params['page'] || 1).to_i - 1
     respond_to do |format|

app/views/admin/homework.html.erb

@@ -22,7 +22,7 @@
         提交作品数
       </th>
       <th style="width: 70px;">
-        提交截止日期
+        作业发布日期
       </th>
     </tr>
     </thead>
@@ -51,7 +51,7 @@
               <%=link_to(StudentWork.where('homework_common_id=?',homework.id).count, student_work_index_path(:homework => homework.id))%>
             </td>
             <td align="center">
-              <%=format_date(homework.end_time) %>
+              <%=format_date( homework.created_at ) %>
             </td>
           </tr>
       <% end %>