Only one imported non-categorized forums (pid=0) will be categorized due to query being overwritten

[yuliu]

In the base forums module's cleanup(): Query $query = $db->simple_select('forums', '*', "type='f' AND pid=0 AND import_fid > 0"); is overwritten when the merge system is trying to rebuild child forums' parentlist:

• $query = $db->simple_select("forums", "fid", "','||parentlist||',' LIKE '%,{$forum['fid']},%'");
• $query = $db->simple_select("forums", "fid", "CONCAT(',',parentlist,',') LIKE '%,{$forum['fid']},%'");
• using it while($child = $db->fetch_array($query)).

[yuliu]

And that makes only the first forum in the SQL's result get categorized. Others will be listed under root without a parent category, which is not allowed in MyBB and "Please select a valid forum" error will occur when trying to grant moderator permissions for them at AdminCP.

Original report: https://community.mybb.com/thread-229919.html