Objective: 以允许分页的方式查询和循环页面的第三级“孙子”。

以下是我正在使用的代码（不包括分页）：

        // Get the ID of the first generation
        $gen1_ids = $post->ID;

        // Query for second generation IDs
        $gen2 = $wpdb->get_col( "SELECT ID FROM $wpdb->posts WHERE $wpdb->posts.post_parent IN ($gen1_ids) AND $wpdb->posts.post_type = \'page\' AND $wpdb->posts.post_status = \'publish\' ORDER BY $wpdb->posts.ID ASC" ); // Test ordering by title

        // Implode the results for further use
        $gen2_ids = implode( $gen2,\', \' );

        // Now, query for third generation IDs using second generation IDs
        $gen3 = $wpdb->get_col( "SELECT ID FROM $wpdb->posts WHERE $wpdb->posts.post_parent IN ($gen2_ids) AND $wpdb->posts.post_type = \'page\' AND $wpdb->posts.post_status = \'publish\' ORDER BY $wpdb->posts.ID ASC" );

        $args = array(
          \'post__in\' => $gen3,
          \'post_type\' => \'page\',
          \'post_status\' => \'publish\',
          \'posts_per_page\' => 5,
          \'paged\' => get_query_var(\'paged\')
        );

        $results = null;
        $results = new WP_Query( $args );

        if( $results->have_posts() ) { 
            while ( $results->have_posts() ) : $results->the_post(); ?>
                <li>
                    <a href="<?php the_permalink(); ?>" class="img"><img src="#"></a>
                    <div class="text">
                        <h3><a href="<?php the_permalink() ?>"><?php the_title(); ?></a></h3>
                        <p>...</p>
                    </div>
                </li>
        <?php endwhile;
        } /* end if */ ?>

     <?php wp_reset_query();  // Restore global post data stomped by the_post(). ?>

两年前，我在WordPress上修改了一个支持问题的答案中的代码。组织论坛。代码正在运行。

有没有办法做得更好？

function wpse_84810_get_grandchildren( $grandparent_id = false ) {
    global $wpdb;

    if ( !$grandparent_id )
        $grandparent_id = get_the_ID();

    $grandchildren_ids = $wpdb->get_col( $wpdb->prepare( "SELECT p1.ID FROM {$wpdb->posts} AS p1 INNER JOIN {$wpdb->posts} AS p2 ON p1.post_parent = p2.ID WHERE p2.post_parent = %d", $grandparent_id ) );

    if ( $grandchildren_ids ) {
        return new WP_Query( array(
            \'post__in\' => $grandchildren_ids,
            \'post_type\' => \'page\',
            \'post_status\' => \'publish\',
            \'posts_per_page\' => 5,
            \'paged\' => get_query_var( \'paged\' ) ? get_query_var( \'paged\' ) : 1
        ) );
    }

    return false;
}