I am attempting to use wpdb class to obtain the publish id in the top-level site inside a Wordpress-MU atmosphere from among the sub-sites utilizing a meta value in the sub site. The next code pulls in the wordpress_2_postmeta table.

$result = $wpdb->get_row("SELECT post_id FROM $wpdb->postmeta WHERE meta_value LIKE '%".$lname."%'");

BUT I wish to pull in the wordpress_postmeta table within the same database. i attempted with explicit prefix: $wpdb->wp_postmeta

That does not work.

How will you specify the wordpress_postmeta table explictly using wpdb with Wordpress MU?

Have you attempt to hardcoded ?

You can test to go in the wordpress_postmeta into the query.

I understand that's not too good solution, but when you create that code for use on your usage you'll be able to check it out )