WordPress: move comments between posts

move_comments.php

<?php
function move_comments( $from_post_id, $to_post_id ) {
  global $wpdb;
  
  $sql = sprintf(
    'UPDATE %s SET comment_post_id=%s WHERE comment_post_id=%s;',
    $wpdb->comments,
    (int) $to_post_id,
    (int) $from_post_id
  );
  
  $wpdb->query( $sql );
}