I'm in the middle of doing some fairly complex queries involving metadata from a custom post type. Unfortunately if any posts are deleted the metadata stays put which complicates matters as I am counting it.
I was wondering how best to go about deleting the orphan metadata in the event that the post is deleted.
Should I include a function that deletes them the database through $wpdb?
I found an SQL query that does just that but I'm not sure how to format it.
DELETE pm FROM wp_postmeta pm LEFT JOIN wp_posts wp ON wp.ID = pm.post_id WHERE wp.ID IS NULL
I tried it in phpmyadmin on a backup copy of my database but to no avail.