Quiz

1) If Moodle can detect that a question is in use, then when you ask to delete it, it just marks it hidden instead of really deleting it.

If a question is marked as hidden, then it can be undeleted.

Unfortunately, the way things are stored in the database, it is almost impossible to tell when a question has been used by a random question. This is MDL-5780.

2) I didn't actually know what happens in this situation. Looking at the code, it seems that it regrades any questions that still exist. Any questions that have been deleted are not regraded, so the score for them is not changed.

3) What happens here is that, on the review screen, it displays this message in place of any question that was deleted. However, the score that the student got when they attempted that question is still stored in the database.


If you want to poke around in the database, then student responses and scores are stored in the mdl_question_states table, and for random questions, the answer column starts random123-, where 123 is the id of the question that the student actually saw. That is, the 123 bit refers to the id column of the mdl_question table.

If you can work out the id of the question that was deleted, suppose it was 123, and suppose you create a new version of this question, and it gets id 234, then you could try a query like

UPDATE mdl_question_states SET answer = REPLACE(answer, 'random123-', 'random234-') WHERE answer LIKE 'random123-%';

However this kind of fiddling around in the database is very dangerous, so only do it if you understand what you are doing, have a full backup, and have practised on a test installation of Moodle first.