php高手帮忙写下返回上一页的代码

php代码：

echo "点击手动返回前一页";

已作修改，看下这样可以不

require("inc/con.php");
include("inc/db_sql.php");
include("inc/config.php");
$link=db_connect();
$empire=new mysqlquery();
$classid=intval($_GET['classid']);
$id=intval($_GET['id']);
$muid=(int)getcvar('userid');//用户id
$musername=RepPostVar(getcvar('mlusername'));//用户名
$musertype=(int)getcvar('mlusertype');//会员组id
if($classid&&$id&&$class_r[$classid]&&$muid)
{
if($muid==1){
$sql1=$empire->query("update info set top=1 where uid='$muid' and id='$id' and classid='$classid' limit 1");
$sql2=$empire->query("update info_member set jifen=jifen-1 where uid='$muid'");
echo "";
exit();

}

}

else{

echo "";
exit();

}
db_close();
$empire=null;
?>