Sorry, I forgot to mark the query as code and some elements got removed in the formatting. Here is the proper format:
Code:
SELECT DISTINCT `id`, `name`
FROM #__classification_parent
WHERE `flag`=1 AND `parent`=0 AND NOT '[cb_reviewer_fiction_favcat]' REGEXP concat('[[:<:]]',`id`,'[[:>:]]')
ORDER BY `name`
Also 'cb_reviewer_fiction_favcat' is the first multi-select query result (the ones that you want to exclude in the second query)