order by pid desc加到这个语句的那个位置？该怎么处理 _PHP

order by pid desc加到这个语句的那个位置？

PHP code

<?php
$sql = "SELECT `subject`, `author`, `fid` ,`first`,`tid`,`pid`  FROM `forum_post` WHERE 1 ";
 $result = mysql_query($sql) or die("查询失败!");  
   $number = 6;
 while ($row=mysql_fetch_array($result)) 
 {
     if ($row['fid'] ==56 && $row['first'] !=0 && $number != 0)
     {
         ?>
         <tr>
            <td><a href="message/mes.php?id=<?php echo $row['pid'];?>"><h3>
            <?php echo substr($row['subject'],0,64);$number--;?></h3></a></td>
               <td><a href="message/mes.php?id=<?php echo $row['pid'];?>"><h3>
            <?php echo substr($row['author'],0,16);?></h3></a></td>
        </tr>
        <?php
     }
}?>

order by pid desc加到这个语句的那个位置？
$sql = "SELECT `subject`, `author`, `fid` ,`first`,`tid`,`pid` FROM `forum_post` WHERE 1 ";
我试了好几个地方都报错。
我需要让他降序排列

------解决方案--------------------
WHERE 1 之后
------解决方案--------------------
SELECT `subject`, `author`, `fid` ,`first`,`tid`,`pid` FROM `forum_post` WHERE 1
order by pid desc
------解决方案--------------------
语句最后，limit之前