Index: question/category_class.php
===================================================================
RCS file: /cvsroot/moodle/moodle/question/category_class.php,v
retrieving revision 1.32.2.3
diff -u -r1.32.2.3 category_class.php
--- question/category_class.php	2 Apr 2008 06:10:05 -0000	1.32.2.3
+++ question/category_class.php	9 May 2008 13:47:59 -0000
@@ -352,8 +352,9 @@
     }
 
     function move_questions($oldcat, $newcat){
-        if (!set_field('question', 'category', $newcat, 'category', $oldcat)) {
-            error("Error while moving questions from category '$oldcat' to '$newcat'", $this->pageurl->out());
+        $questionids = get_records_select_menu('question', "category = $oldcat AND parent = 0", '', 'id,1');
+        if (!question_move_questions_to_category(implode(',', array_keys($questionids)), $newcat)) {
+            print_error('errormovingquestions', 'question', $returnurl, $ids);
         }
     }
 
Index: question/contextmoveq.php
===================================================================
RCS file: /cvsroot/moodle/moodle/question/contextmoveq.php,v
retrieving revision 1.4.2.2
diff -u -r1.4.2.2 contextmoveq.php
--- question/contextmoveq.php	20 Dec 2007 11:26:50 -0000	1.4.2.2
+++ question/contextmoveq.php	9 May 2008 13:47:59 -0000
@@ -159,9 +159,10 @@
 
         }
     }
-    //now move questions
-    if (!execute_sql("UPDATE {$CFG->prefix}question SET category = {$tocat->id} WHERE id IN ({$ids})", false)){
-        error("Could not move the questions {$ids} to category ".$tocat->name, $returnurl);
+
+/// Now move questions.
+    if (!question_move_questions_to_category(implode(',', $ids), $tocat->id)) {
+        print_error('errormovingquestions', 'question', $returnurl, $ids);
     }
     redirect($returnurl);
 }
Index: question/editlib.php
===================================================================
RCS file: /cvsroot/moodle/moodle/question/editlib.php,v
retrieving revision 1.76.2.7
diff -u -r1.76.2.7 editlib.php
--- question/editlib.php	23 Apr 2008 13:45:40 -0000	1.76.2.7
+++ question/editlib.php	9 May 2008 13:47:59 -0000
@@ -447,11 +447,8 @@
             }
             $returnurl = $pageurl->out(false, array('category'=>"$tocategoryid,$contextid"));
             if (!$checkforfiles){
-                foreach ($questionids as $questionid){
-                    //move question
-                    if (!set_field('question', 'category', $tocategory->id, 'id', $questionid)) {
-                        error('Could not update category field');
-                    }
+                if (!question_move_questions_to_category(implode(',', $questionids), $tocategory->id)) {
+                    print_error('errormovingquestions', 'question', $returnurl, $questionids);
                 }
                 redirect($returnurl);
             } else {
Index: lib/questionlib.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lib/questionlib.php,v
retrieving revision 1.119.2.5
diff -u -r1.119.2.5 questionlib.php
--- lib/questionlib.php	28 Feb 2008 12:52:59 -0000	1.119.2.5
+++ lib/questionlib.php	9 May 2008 13:47:59 -0000
@@ -559,6 +559,30 @@
     }
     return true;
 }
+
+/**
+ * This function should be considered private to the question bank, it is called from
+ * question/editlib.php question/contextmoveq.php and a few similar places to to the work of
+ * acutally moving questions and associated data. However, callers of this function also have to
+ * do other work, which is why you should not call this method directly from outside the questionbank.
+ *
+ * @param string $questionids a comma-separated list of question ids.
+ * @param integer $newcategory the id of the category to move to.
+ */
+function question_move_questions_to_category($questionids, $newcategory) {
+    $result = true;
+
+    // Move the questions themselves.
+    $result = $result && set_field_select('question', 'category', $newcategory, "id IN ($questionids)");
+
+    // Move any subquestions belonging to them.
+    $result = $result && set_field_select('question', 'category', $newcategory, "parent IN ($questionids)");
+
+    // TODO Deal with datasets.
+    
+    return $result;
+}
+
 /**
  * @param array $row tab objects
  * @param question_edit_contexts $contexts object representing contexts available from this context
Index: lang/en_utf8/question.php
===================================================================
RCS file: /cvsroot/moodle/moodle/lang/en_utf8/question.php,v
retrieving revision 1.7
diff -u -r1.7 question.php
--- lang/en_utf8/question.php	21 Aug 2007 06:55:49 -0000	1.7
+++ lang/en_utf8/question.php	9 May 2008 13:47:58 -0000
@@ -32,6 +32,7 @@
 $string['erroraccessingcontext'] = 'Cannot access context';
 $string['errorfilecannotbecopied'] = 'Error cannot copy file $a.';
 $string['errorfilecannotbemoved'] = 'Error cannot move file $a.';
+$string['errormovingquestions'] = 'Error while moving questions with ids $a.';
 $string['errorfileschanged'] = 'Error files linked to from questions have changed since form was displayed.';
 $string['exportcategory'] = 'Export category';
 $string['filesareasite']= 'the site files area';