在wordpress中更改帖子值

Question

How change existing value to new and keep data ?

I changed the name in acf and now my new data is not updated

$post_desc = get_post_meta(get_the_ID(), 'post_desc', true);
$post_id = get_the_ID();

$value = get_post_custom_values(get_the_ID(), $post_desc);
    foreach ($value as $values)
        update_post_meta( $post_id, 'post_desc', $post_desc );

post_desc - is new name on acf