Missatges enviats per Visvanath Ratnaweera

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Success! Thank you!

I didn't do anything new. Just repeated the exercise of restoring the table mdl_course_categories in the 5.1 with a dump taken from the 4.5. Again I got the 'Unknown category with category ID number "1"' error as in the OP but this time purged all caches!

Now I'm getting the course structure in 4.5 reconstructed in 5.1. Not yet declaring "resolved", waiting for any adverse effects.

Note that the "truncate mdl_course_categories" is superfluous, since the restore drops the table and re-creates it.
 
Another
> In the GUI, edit that category and set it to TOP - Set Parent Category - SAVE
 
Can't find that in the GUI. I didn't need it. Just FYI.
 
> And I'll say again, don't know why one needs that! Somrient
 
Only a selection of courses will be transferred to the new (5.1) site based on a list of course id, category id - of course scripted. The category id there will be the category id in the old (4.5); if the ids change, there is no way of knowing the future category id!
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Hi Ken

Your exploit sounds adventurous. Of course the target (5.1) site is a test site, so no risks.

But I can't follow your idea completely. You wrote:

In the 4.5 dump the table to an sql file.
Xfer that file to the 5.1

In 5.1 from mysql client

use DB
truncate  mdl_course_categories;
\q

Then import the sql dump of that table taken from the 4.5
mysql -u root comptest < 45coursecats.sql

That is almost the same I did originally except for the truncate. Will repeat this time with the truncate.

The ONLY one that came in was the first category ... 

Can you be more specific? Do you mean, the table will have only a single row, the "(31,'Grundlagen','','',1,0,10000,0,1,1,1540889739,1,'/31',NULL)"?

HOWEVER ...

Edit;
Set Parent Category to Top
Save changes
ALL imported cats show up

What do I edit? 45coursecats.sql before importing? Or, do you mean something I need to do inside the 'mysql' interactive tool, talking to the 5.1 database?

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Upgrading and cleaning is out of the question. Why? Then I can as well clean the current version.

Let's see, whether somebody knows the database model to explain why my original idea, https://moodle.org/mod/forum/discuss.php?d=474327, does not work and how to correct it.
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Generally speaking an investigation on an alleged cheater can go in three directions:
1. Technical issues outside Moodle
Typically, network issues or the server overloaded. Theoretically incompatible browsers may also play a role, but if the students use the latest version of a mainstream browser, less likely.

2. The quiz is not optimally set
There are simply too many setting in the Moodle quiz/questions module. It needs a lot of practice.
 
3. The student has indeed found a hole
 
On 1), your system administrators and network administrators must talk. They should have deep monitoring in place whose records they or experts can study after an incidence.
 
On 2), I would analyze the two quizzes in detail. Certain statements you made, make me think that this is viable. 
 
Example 1. " the teacher asked us (the invigilators) to do the initial calculations of multiple choice questions". Why, Moodle has a sophisticated grade book built in.
 
Example 2. "However, the student had re-entered the exam, after they have left the room." I assume, you don't want that. Then how was it possible? You must have missed a setting. Strictly speaking, Moodle may have a bug. But I can't imaging it having such a glaring bug, the quiz module is used intensively all over the world. Even if there is one, you must document a way for us to reproduce the behaviour. 
 
On 3), that is also viable. There are always ingenious students - or at a minimum, they just need the resources to surprise the teacher/invigilators.
 
 
As Tim already stated, you can't be 100% certain in a passed incidence, not even 99.9%. You'll have better chances in a human engineering approach, if you could make him to talk somehow...
Complicitat
 
Not joking. Don't underestimate the value of a confession. You'll save an unknown number of future incidents.