PDO Sql语句顺序错误

<?php 
require('db_info.php');
$recordsPerPage = 5;
if (isset($_GET['page']))
  $curPage = $_GET['page'];
else
      $curPage = 1;
  $startIndex = ($curPage-1) * $recordsPerPage;
try {
       $pdoObject = new PDO("mysql:host=$dbhost; dbname=$dbname;", $dbuser, $dbpass);
   $sql = "SELECT count(id) FROM usercom";
   $statement = $pdoObject->query($sql); 
   $record = $statement->fetch(PDO::FETCH_ASSOC);
   $pages = ceil($record['count(id)']/$recordsPerPage);
   $record=null;
   $sql = "SELECT * FROM usercom LIMIT $startIndex, $recordsPerPage ORDER BY date DESC";
   $statement = $pdoObject->query($sql);
   while ( $record = $statement->fetch(PDO::FETCH_ASSOC) ) {
   echo '<p>'.$record['date'].'<br/>'.$record['userComment'].'<br/>';
                }

   $statement->closeCursor();
   $pdoObject = null;
   } catch (PDOException $e) {
   echo 'PDO Exception: '.$e->getMessage();
    die();
   }?></p>

我试图从数据库中获取结果并使用分页。问题是，语句中要求的降序永远不适用。为什么这不起作用?如果我不添加"ORDER BY date DESC"行，它工作得很好，但当我这样做时，它打印错误，我试图获取一个非对象。