php实现只保留mysql中最新1000条记录

<?php 
mysql_connect("localhost","root","root");
mysql_select_db("test");
//保存最新的1000条记载
$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;
$result=mysql_query($query);
mysql_data_seek($result,$limit-1);
$data=mysql_fetch_array($result);
$query="delete from `news` where `id`<"$data[id]"";
if(mysql_query($query)){
echo "数据库中原有".$num."条记载，过剩的".($num-$limit)."条记载被胜利删除，现在还剩余".$limit."条记载！";
}
}else{
echo "数据记载不足".$limit."条！没有必要删除！";
}
?>


<?php 
mysql_connect("