diff --git a/app/controllers/statistics_controller.rb b/app/controllers/statistics_controller.rb
index beebb331c..914169a13 100644
--- a/app/controllers/statistics_controller.rb
+++ b/app/controllers/statistics_controller.rb
@@ -9,20 +9,17 @@ class StatisticsController < ApplicationController
   before_filter :require_manager, :only =>[:edit, :update, :destroy]
 
   def index
-    type = (params[:type] == "reorder_popu" ? "size" : "created_at")
+    type = (params[:type] == "reorder_popu" ? "file_size" : "created_at")
     order = (params[:order] == "asc" ? "asc" : "desc")
     if params[:sub_category_id].present?
       @statistics = Statistic.where(:sub_category_id => params[:sub_category_id])
       sub_category_id =  '(' + params[:sub_category_id].to_a.join(",") + ')'
-      @statistics = Statistic.find_by_sql("SELECT statistics.*, (select sum(filesize) from attachments where attachments.container_type='Statistic' and
-                                         attachments.container_id = statistics.id group by attachments.container_id) as size from statistics where sub_category_id in #{sub_category_id} order by #{type} #{order}")
+      @statistics = Statistic.find_by_sql("SELECT statistics.* from statistics where sub_category_id in #{sub_category_id} order by #{type} #{order}")
     else
       if params[:main_category_id].present?
-        @statistics = Statistic.find_by_sql("SELECT statistics.*, (select sum(filesize) from attachments where attachments.container_type='Statistic' and
-                                         attachments.container_id = statistics.id group by attachments.container_id) as size from statistics where main_category_id = #{params[:main_category_id]} order by #{type} #{order}")
+        @statistics = Statistic.find_by_sql("SELECT statistics.* from statistics where main_category_id = #{params[:main_category_id]} order by #{type} #{order}")
       else
-        @statistics = Statistic.find_by_sql("SELECT statistics.*, (select sum(filesize) from attachments where attachments.container_type='Statistic' and
-                                         attachments.container_id = statistics.id group by attachments.container_id) as size from statistics order by #{type} #{order}")
+        @statistics = Statistic.find_by_sql("SELECT statistics.* from statistics order by #{type} #{order}")
       end
     end
     @statistics_count = @statistics.count
@@ -78,6 +75,9 @@ class StatisticsController < ApplicationController
     @statistic.save_attachments_containers(params[:attachments], User.current, true)
     respond_to do |format|
       if @statistic.save
+        if @statistic.file_size.nil? && @statistic.attachments.count > 0
+          @statistic.update_attribute('file_size', format("%0.3f", @statistic.attachments.map{|c| c.filesize}.sum.to_f/(1024*1024)))
+        end
         format.html { redirect_to @statistic, notice: '创建成功' }
         format.json { render json: @statistic, status: :created, location: @statistic }
       else
@@ -102,6 +102,10 @@ class StatisticsController < ApplicationController
             end
           end
         end
+
+        if @statistic.file_size.nil? && @statistic.attachments.count > 0
+          @statistic.update_attribute('file_size', format("%0.3f", @statistic.attachments.map{|c| c.filesize}.sum.to_f/(1024*1024)))
+        end
         
         format.html { redirect_to @statistic, notice: '更新成功' }
         format.json { head :no_content }
diff --git a/app/models/statistic.rb b/app/models/statistic.rb
index 2302bd37c..15fafa270 100644
--- a/app/models/statistic.rb
+++ b/app/models/statistic.rb
@@ -1,5 +1,5 @@
 class Statistic < ActiveRecord::Base
-  attr_accessible :description, :name, :status, :user_id, :main_category_id, :sub_category_id
+  attr_accessible :description, :name, :status, :user_id, :main_category_id, :sub_category_id, :file_size
   acts_as_attachable
 
   validates_presence_of :main_category_id
diff --git a/app/views/statistics/_form.html.erb b/app/views/statistics/_form.html.erb
index 40bac0afa..6e18228c0 100644
--- a/app/views/statistics/_form.html.erb
+++ b/app/views/statistics/_form.html.erb
@@ -31,9 +31,9 @@
         </div>
       </div>
       <div class="field line_field">
-        <label class="field_lab"><span>*</span>数据源大小：</label>
-        <%= f.text_field :name, :class => "wb85" %>
-        <p class="cl" style="padding-left: 10%;color: red;height: 20px"><span id="input_name_notice" class="none">请输入数据名称</span></p>
+        <label class="field_lab">数据大小：</label>
+        <%= f.text_field :file_size, :placeholder => "单位：M", :class => "wb85" %>
+        <p class="cl" style="padding-left: 10%;color: red;height: 20px"><span id="input_file_size_notice" class="none">请输入正数</span></p>
       </div>
 
       <div class="field line_field">
@@ -112,10 +112,14 @@
 
     function submit_cate(){
         var name=$("#statistic_name").val();
+        var file_size=$("#statistic_file_size").val().trim();
         var cate=$("#statistic_main_category_id option:selected").text();
         if(name == ""){
             $("#input_name_notice").removeClass("none");
             return;
+        } else if(file_size != "" && !/^(?:[1-9][0-9]*\.[0-9]+|0\.(?!0+$)[0-9]+|[1-9]+\d*)$/.test(file_size)){
+            $("#input_file_size_notice").show();
+            return;
         }
         $("#new_statistic").submit();
         $("#edit_statistic_<%= @statistic.id %>").submit();
diff --git a/app/views/statistics/_statistics_list.html.erb b/app/views/statistics/_statistics_list.html.erb
index 34985a166..718d2096d 100644
--- a/app/views/statistics/_statistics_list.html.erb
+++ b/app/views/statistics/_statistics_list.html.erb
@@ -25,8 +25,8 @@
           <% if statistic.sub_category.present? %>
             <span><%= statistic.sub_category.try(:name) %></span>
           <% end %>
-          <% if statistic.size.present? %>
-              <span><%= number_to_human_size statistic.size %>&nbsp;Bytes</span>
+          <% if statistic.file_size.present? %>
+              <span><%= statistic.file_size %>&nbsp;MB</span>
           <% end %>
           <span><%= format_time statistic.created_at %></span>
         </div>
diff --git a/db/migrate/20180504075834_add_file_size_to_statistics.rb b/db/migrate/20180504075834_add_file_size_to_statistics.rb
new file mode 100644
index 000000000..77bf20dd0
--- /dev/null
+++ b/db/migrate/20180504075834_add_file_size_to_statistics.rb
@@ -0,0 +1,11 @@
+class AddFileSizeToStatistics < ActiveRecord::Migration
+  def change
+    add_column :statistics, :file_size, :float
+
+    Statistic.all.each do |statistic|
+      if statistic.attachments.count > 0
+        statistic.update_attribute('file_size', format("%0.3f",statistic.attachments.map{|c| c.filesize}.sum.to_f/(1024*1024)))
+      end
+    end
+  end
+end
diff --git a/db/schema.rb b/db/schema.rb
index df52a9a2b..e4a3dccca 100644
--- a/db/schema.rb
+++ b/db/schema.rb
@@ -11,7 +11,7 @@
 #
 # It's strongly recommended to check this file into your version control system.
 
-ActiveRecord::Schema.define(:version => 20180207065530) do
+ActiveRecord::Schema.define(:version => 20180504075834) do
 
   create_table "activities", :force => true do |t|
     t.integer  "act_id",                                  :null => false
@@ -1133,6 +1133,9 @@ ActiveRecord::Schema.define(:version => 20180207065530) do
     t.integer  "score",                :default => -1
   end
 
+  add_index "exercise_answers", ["exercise_choice_id"], :name => "ec"
+  add_index "exercise_answers", ["exercise_question_id", "user_id"], :name => "ea"
+
   create_table "exercise_bank_choices", :force => true do |t|
     t.integer  "exercise_bank_question_id"
     t.text     "choice_text"
@@ -1221,6 +1224,8 @@ ActiveRecord::Schema.define(:version => 20180207065530) do
     t.integer  "subjective_score", :default => -1
   end
 
+  add_index "exercise_users", ["exercise_id"], :name => "index_exercise_users_on_exercise_id"
+
   create_table "exercises", :force => true do |t|
     t.text     "exercise_name"
     t.text     "exercise_description"