To tester: For bonus points you can write a unit testcase for this fix and i'll integrate it (Dan) Testing difficulty: Hard(requires writing code to test) With a quiz that has completed attempts: Construct a query usings the qubaids_for_quiz object with $finishedonly set to true, below is an included snippet that led to finding this bug: $qubaids = new qubaids_for_quiz($quizid, false, true); $questionids = $DB->get_fieldset_select('question_attempts', 'questionid', 'questionusageid ' . $qubaids->usage_id_in(), $qubaids->usage_id_in_params());   Without the patch it should exhibit a dml exception with the patch you should get a list of question ids.