批量将WordPress更新时间改为发帖时间

代码如下，放到WordPress根目录，然后访问一次就好：

<?php
include("wp-load.php");
$posts= $wpdb->get_results("SELECT * FROM `wp_posts`");
$i=0;
foreach ($posts as $post){
    $i++;
    $postid = $post->ID;
    $post_date = $post->post_date;//发帖时间
    $wpdb->get_results("UPDATE `wp_`.`wp_posts` SET `post_modified` = '$post_date' WHERE `wp_posts`.`ID` = $postid");
    $wpdb->get_results("UPDATE `wp_`.`wp_posts` SET `post_modified_gmt` = '$post_date' WHERE `wp_posts`.`ID` = $postid");
}
echo $i;