Wordpress上仅显示Ping（Pingbacks + Trackbacks）数字

<?php
global $wpdb;
$post_id = get_the_ID();
$total_ping_count = $wpdb->get_var("SELECT count(comment_id) FROM $wpdb->comments WHERE comment_type = 'pingback'");
$total_approved_pings = $wpdb->get_var("SELECT count(comment_id) FROM $wpdb->comments WHERE comment_type = 'pingback' and comment_approved = 1");
$post_ping_count = $wpdb->get_var("SELECT count(comment_id) FROM $wpdb->comments WHERE comment_type = 'pingback' and comment_approved = 1 and comment_post_id = $post_id");
echo "The total number of pings on this site is $total_ping_count.n";
echo "The total number of approved pings on this site is $total_approved_pings.n";
echo "The total number of approved pings on this post is $post_ping_count.n";
?>

comment_type = 'pingback'

comment_type = 'trackback'

comment_type IN ('pingback', 'trackback')