您需要的功能是wp_update_post().

您可能希望有您想要更新的帖子，然后设置一个循环来分别更新每个帖子。

// However you get your posts, ID\'s, etc.
$posts = get_posts( array( \'post_type\' => \'post\' ) );

for ( $posts as $post ) {
    wp_update_post( array( \'ID\' => $post->ID, \'post_parent\' => 8 ) );
}

global $wpdb;

$query = $wpdb->prepare( \'UPDATE wp_posts SET post_parent = %d WHERE post_type = %s\', 8, \'my-post-type\' );

$wpdb->query( $query );