How to get taxonomy terms in Wordpress that contain posts with a certain meta field?

Question

WordPress

Good afternoon!
I'm confused about getting the taxonomy terms that contain posts with a certain meta field.
For example, posts have a "country" meta field. So we need to get the terms whose posts have the country" meta field with the value "RU". Help, please, who faced a similar task.

Answer 1

$wpdb->query() and here we write a SQL query with 3 JOINs
as the so

...
left join wp_postmeta as pm
  on p.ID = pm.post_id
left join wp_term_relationships as tr
  on tr.object_id = p.ID
left join wp_terms as t
  on tr.term_taxonomy_id = t.term_id
...