php实现只保留mysql中最新1000条记录

<?php mysql_connect(localhost,root,root); mysql_select_db(test); //保留最新的1000条记录 $limit=1000; $query=select `id` from `news`; $result=mysql_query($query); $num=mysql_num_rows($result); if($num>$limit){ $query=select `id` from `news` order by `id` desc limit .$limit; $result=mysql_query($q