Question

If I delete an user, what happens with his questions, answers and comments?

Comments

I think they all become 'anonymous' but I'm not sure.

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I've read the Core files, his Q, A & C will be deleted.

Answer 1

You could just 'block' them. This leaves them in the db, and their user id still owns the posts.

Answer 2

In the function qa_db_user_delete($userid) of the qa-db-users.php , it tells that all things of the user will be deleted.

        qa_db_query_sub('UPDATE ^posts SET lastuserid=NULL WHERE lastuserid=$', $userid);
        qa_db_query_sub('DELETE FROM ^userpoints WHERE userid=$', $userid);
        qa_db_query_sub('DELETE FROM ^blobs WHERE blobid=(SELECT avatarblobid FROM ^users WHERE userid=$)', $userid);
        qa_db_query_sub('DELETE FROM ^users WHERE userid=$', $userid);
        qa_db_query_sub('UPDATE ^posts SET userid=NULL WHERE userid=$', $userid);
        qa_db_query_sub('DELETE FROM ^userlogins WHERE userid=$', $userid);
        qa_db_query_sub('DELETE FROM ^userprofile WHERE userid=$', $userid);
        qa_db_query_sub('DELETE FROM ^userfavorites WHERE userid=$', $userid);
        qa_db_query_sub('DELETE FROM ^userevents WHERE userid=$', $userid);
        qa_db_query_sub('DELETE FROM ^uservotes WHERE userid=$', $userid);
        qa_db_query_sub('DELETE FROM ^userlimits WHERE userid=$', $userid);