$result = mysql_query("UPDATE dle_post SET xfields='$xfields' WHERE id=$id ") or die("ERROR!!!");

mysql_query("UPDATE dle_post SET xfields='$xfields' WHERE id=$id ") or die("ERROR!!!");

<?
$db = mysql_connect('localhost','user','pass');
mysql_query ("set character_set_client='cp1251'");
mysql_query ("set character_set_results='cp1251'");
mysql_query ("set collation_connection='cp1251_general_ci'");
mysql_select_db("base",$db);

$result = mysql_query("SELECT `id`, `date`, `editdate`, `xfields` FROM dle_post",$db);
$post = mysql_fetch_array($result);
?>

<?php
include "db.php";

// Константы{
$i = 0;
// }Константы

do
{
$id = $post["id"];
$i++;
$xfields = $post["xfields"]."||del|Удалена";

echo $i.". ".$post['id'].". ";

//Здесь много вычислительного кода
        
        if ( $workdateyear == date("Y") )
        {
            if ( date("z") - $workdate > 11 )
            {
                $result = mysql_query("UPDATE dle_post SET xfields='$xfields' WHERE id=$id ") or die("ERROR!!!");

                echo "Изменения произведены";
            }
        }

echo "<br />";

}
while ($post = mysql_fetch_array($result));
?>

while ($post = mysql_fetch_array($result));

$result = mysql_query("UPDATE dle_post SET xfields='$xfields' WHERE id=$id ") or die("ERROR!!!");