Question

in simple I try do that in PhpMyAdmin:

update wp_postmeta.meta_value = wp_posts.id where

wp_posts.post_name=articles.image

AND wp_posts.post_type=attachment

AND wp_postmeta.meta_key=_thumbnail_id

by this MySQL query:

update wp_postmeta m
join articles a on (m.post_id = a.id)
join wp_posts p on (m.post_id = p.ID)
set m.meta_value = p.ID
where p.post_name=a.image
AND a.image != NULL
AND p.post_type='attachment'
AND m.meta_key='_thumbnail_id'

it’s work but 0 rows affected!
anyone can help?

Answer 1

Use subqueries with Andomar’s answer. Using joins with update and delete statements is not good.

It should be something like

UPDATE wp_postmeta m SET m.meta_value = (SELECT p.ID FROM wp_posts p, articles a 
WHERE m.post_id=p.ID AND m.post_id = a.id AND a.image IS NOT NULL 
   AND p.post_type='attachment' AND p.post_name=a.image) 
WHERE m.meta_key='_thumbnail_id'

BACKUP FIRST! I didn’t test this.

If doesn’t work try to execute a select query if you can select them. If it doesn’t select (and probably it won’t) please check the structure of your query corresponding to your design.

SELECT m.meta_value, (SELECT p.ID FROM wp_posts p, articles a 
WHERE m.post_id=p.ID AND m.post_id = a.id AND a.image IS NOT NULL 
   AND p.post_type='attachment' AND p.post_name=a.image)  AS pID
FROM wp_postmeta m
WHERE m.meta_key='_thumbnail_id'

Also try your first query too

SELECT m.meta_value, p.ID AS pID FROM wp_postmeta m
INNER JOIN articles a on (m.post_id = a.id)
INNER JOIN wp_posts p on (m.post_id = p.ID)
WHERE p.post_name=a.image
AND a.image IS NOT NULL
AND p.post_type='attachment'
AND m.meta_key='_thumbnail_id'

Try to play with/modify the select queries to find out the problem.