我已经做了更多的研究，并阅读了下面的文章，这篇文章正是我想要它做的。根据作者的说法，代码是可行的，但当我尝试根据自己的情况调整代码时，它不会更新帖子状态。有人能告诉我我做错了什么吗？

原始代码：

$ap = get_post_meta($post->ID,\'sub_seminars_0_start_date\',true);
$startdate = date("Ymd", strtotime($ap));
$todaydate = date("Ymd");
if(strtotime($todaydate) > strtotime($startdate) && !empty($ap)){
    $del_data = array(
                \'Ref\' => \'sub_seminars_0_ref\',
                \'Start date\' => \'sub_seminars_0_start_date\',
                \'End Date\' => \'sub_seminars_0_end_date\',
                \'Venue\' => \'sub_seminars_0_venue\',
                \'Fees\' => \'sub_seminars_0_fees\',
                \'CPE Credits\' => \'sub_seminars_0_cpe_credits\'
    );
delete_row(\'sub_seminars\', 1);

function expire_posts () {
    $post_id = get_the_ID();
    $getdate = get_post_meta($post_id, \'Expiry Date\', true);
    $expirydate = date ( \'d F Y\', strtotime ($getdate));
    $today = date( \'d F Y\' );
    if ( strtotime($expirydate) < strtotime($today) ) {
        $postdata = ( array (
                \'ID\' => $post_id,
                \'post_status\' => \'expired\',
                \'post_modified\' => $today,
                )
            );
        wp_update_post ($postdata);
    }
}