From a9ff9f96bdf3fee15afd7fa376fd85b3c3046a27 Mon Sep 17 00:00:00 2001
From: sw <939547590@qq.com>
Date: Fri, 19 Jun 2015 16:23:28 +0800
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---
 app/controllers/student_work_controller.rb | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/app/controllers/student_work_controller.rb b/app/controllers/student_work_controller.rb
index 3ca836773..2693eea82 100644
--- a/app/controllers/student_work_controller.rb
+++ b/app/controllers/student_work_controller.rb
@@ -245,15 +245,19 @@ class StudentWorkController < ApplicationController
   def student_work_absence_penalty
     render_403 unless User.current.allowed_to?(:as_teacher,@course)
     order = params[:order] || "desc"
-    work_ids = "(" + @homework.student_works.map(&:id).join(",") + ")"
-    @stundet_works = StudentWork.find_by_sql("SELECT *,(all_count - has_count) AS absence FROM(
+    if @homework.student_works.empty?
+      @stundet_works = []
+    else
+      work_ids = "(" + @homework.student_works.map(&:id).join(",") + ")"
+      @stundet_works = StudentWork.find_by_sql("SELECT *,(all_count - has_count) AS absence FROM(
       SELECT * ,
         (SELECT COUNT(*) FROM `student_works_evaluation_distributions` WHERE user_id = student_works.user_id AND student_work_id IN #{work_ids}) AS all_count,
         (SELECT COUNT(*) FROM `student_works_scores` WHERE user_id = student_works.user_id AND student_work_id IN #{work_ids}) AS has_count
       FROM `student_works`
       WHERE homework_common_id = #{@homework.id}
-    ) AS table_1
-    ORDER BY absence #{order}")
+      ) AS table_1
+      ORDER BY absence #{order}")
+    end
     @order = order == "desc" ? "asc" : "desc"
     respond_to do |format|
       format.html