如何为WordPress文章添加历史上的今天列表

//历史上的今天，代码来自柳城博主的 WP-Today 插件
function wp_today(){
    global $wpdb;
    $post_year = get_the_time('Y');
    $post_month = get_the_time('m');
    $post_day = get_the_time('j');
    $sql = "select ID, year(post_date_gmt) as h_year, post_title, comment_count FROM 
            $wpdb->posts WHERE post_password = '' AND post_type = 'post' AND post_status = 'publish'
            AND year(post_date_gmt)!='$post_year' AND month(post_date_gmt)='$post_month' AND day(post_date_gmt)='$post_day'
            order by post_date_gmt DESC limit 5";
    $histtory_post = $wpdb->get_results($sql);
    if( $histtory_post ){
        foreach( $histtory_post as $post ){
            $h_year = $post->h_year;
            $h_post_title = $post->post_title;
            $h_permalink = get_permalink( $post->ID );
            $h_comments = $post->comment_count;
            $h_post .= "<li><strong>$h_year:</strong>  <a href='".$h_permalink."' title='".$h_post_title."' target='_blank' rel="noopener">$h_post_title($h_comments)</a></li>";
        }
    }
    if ( $h_post ){
        $result = "<h2>历史上的今天:</h2><ul>".$h_post."</ul>";
    }
    return $result;
}
function wp_today_auto($content){
    if( is_single() ){
        $content = $content.wp_today();
    }
    return $content;
}
add_filter('the_content', 'wp_today_auto',9999);

function wp_today_auto($content){
        if( is_single() ){
            $content = $content.wp_today();
        }
        return $content;
    }
add_filter('the_content', 'wp_today_auto',9999);

<?php echo wp_today(); ?>