thanks a lot John.
I have this query to view the postmeta files that do not have any post relation
SELECT * FROM wp_postmeta pm LEFT JOIN wp_posts wp ON wp.ID = pm.post_id WHERE wp.ID IS NULL
But the query do not show only the advanced custom fields files.
On the next query I have added the acf field to select only these fields
SELECT * FROM wp_postmeta pm LEFT JOIN wp_posts wp ON wp.ID = pm.post_id WHERE wp.ID IS NULL AND pm.meta_key LIKE '%my-custom-field-name%'
And now I would like to know if the query is correct and i can make the delete query without problems and errors on my wordpress after
DELETE FROM wp_postmeta pm LEFT JOIN wp_posts wp ON wp.ID = pm.post_id WHERE wp.ID IS NULL AND pm.meta_key LIKE '%my-custom-field-name%'
