Check if question code is unique see BT#15230

main/exercise/export/aiken/aiken_import.inc.php

@@ -197,7 +197,10 @@ function aiken_import_exercise($file)
             $question->save($exercise);
 
             if (isset($question_array['code'])) {
-                $question->addCode($question_array['code']);
+                $result = $question->addCode($question_array['code']);
+                if (empty($result)) {
+                    Display::addFlash(Display::return_message(get_lang('QuestionCodeNotSaved')));
+                }
             }
 
             $last_question_id = $question->selectId();

main/exercise/question.class.php

@@ -1761,14 +1761,16 @@ abstract class Question
         //Save normal question if NOT media
         if ($this->type != MEDIA_QUESTION) {
             $this->save($exercise);
-
-            if (api_is_platform_admin()) {
-                $this->addCode($form->getSubmitValue('code'));
-            }
-
             // modify the exercise
             $exercise->addToList($this->id);
             $exercise->update_question_positions();
+
+            if (api_is_platform_admin()) {
+                $result = $this->addCode($form->getSubmitValue('code'));
+                if (empty($result)) {
+                    Display::addFlash(Display::return_message(get_lang('QuestionCodeNotSaved')));
+                }
+            }
         }
     }
 
@@ -2379,12 +2381,19 @@ abstract class Question
         if (api_get_configuration_value('allow_question_code') && !empty($this->id)) {
             $code = Database::escape_string($code);
             $table = Database::get_course_table(TABLE_QUIZ_QUESTION);
+
+            $sql = "SELECT * FROM $table WHERE code = '$code' AND iid <> {$this->id}  ";
+            $result = Database::query($sql);
+            $rows = Database::num_rows($result);
+
+            if (empty($rows)) {
                 $sql = "UPDATE $table SET code = '$code' 
                         WHERE iid = {$this->id} AND c_id = {$this->course['real_id']}";
                 Database::query($sql);
 
                 return true;
             }
+        }
 
         return false;
     }