List custom field values in alphabetical order without repetition from the current category?

October 14, 2022 by Tarik Billa

what you could do is:
1. get the list of all posts currently on the page
2. grab all the IDs of the posts
3. do the following query:

SELECT DISTINCT meta_value FROM $wpdb->postmeta WHERE meta_key = 'product_brand' AND post_id IN (3,9,10,15) ORDER BY meta_value;

where 3,9,10,15 are post ids that you’ve collected.