评价逻辑

@@ -331,10 +331,12 @@ class Course extends Api
 
         $star = $star1+$star2;
 
-        foreach ($star as $key => $row) {
-            $create_time[$key] = $row['create_time'];
+        if(!empty($star)){
+            foreach ($star as $key => $row) {
+                $create_time[$key] = $row['create_time'];
+            }
+            array_multisort($create_time, SORT_DESC, $star);
         }
-        array_multisort($create_time, SORT_DESC, $star);
 
         $course['star'] = $star;