php 分页

$sql = "select * from columns_cat order by id desc";
$query = mysql_query($sql);

$sql="select * from columns_cat";
$rs=mysql_query($sql);
$recordcount=mysql_num_rows($rs);
$pagesize=4;
$pagecount=($recordcount-1)/$pagesize+1;
$pagecount=(int)$pagecount;
$page=$_GET["page"];
if($page<1)
{
$page=1;
}
if($page>$pagecount)
{
$page=$pagecount;
}
$startno=($page-1)*$pagesize;
$sql="select * from columns_cat order by id desc limit $startno,$pagesize";
$rs=mysql_query($sql);