Detect and remove unused images in WordPress

detect-unused-images.sql

SELECT
  *
FROM
  wp_posts i
WHERE
  i.post_type = 'attachment'
  AND
  NOT EXISTS (SELECT * FROM wp_posts p WHERE p.ID = i.post_parent)
  AND
  NOT EXISTS (SELECT * FROM wp_postmeta pm WHERE pm.meta_key = '_thumbnail_id' AND pm.meta_value = i.ID)
  AND
  NOT EXISTS (SELECT * FROM wp_posts p WHERE p.post_type <> 'attachment' AND p.post_content LIKE CONCAT('%',i.guid,'%'))
  AND
  NOT EXISTS (SELECT * FROM wp_postmeta pm WHERE pm.meta_value LIKE CONCAT('%',i.guid,'%'))