Thanks! much appreciated. This looks like it may set ALL threads to that prefix instead of just threads without a prefix, but what do I know. :-) I'll test it out before using it in a critical forum and report back.
--------------- Added [DATE]1517934535[/DATE] at [TIME]1517934535[/TIME] ---------------
This worked with a slight modification to achive my desired results:
Code:
UPDATE vb_thread SET prefixid = '1' WHERE forumid = 10 and prefixid <> '3' and prefixid <> '2'
All good now. Thanks.