php 用户登录代码

error_reporting(0);
if(isset($_post['post']) && $_post['post']=="1"){
$mysql教程_servername = "localhost"; 
$mysql_username = "root"; 
$mysql_password =""; 
$mysql_database ="peng"; 
mysql_connect($mysql_servername , $mysql_username , $mysql_password);
mysql_select_db($mysql_database); 
$name=$_post['name'];
$passowrd=$_post['password'];

if ($name && $passowrd){
 $sql = "select * from liuyanban where name = '$name' and password='$passowrd'";
 $res = mysql_query($sql);
 $rows=mysql_num_rows($res);
  if($rows){
  header("refresh:0;url=a.htm");
  exit;
 }
 echo "";
}else {
 echo "";
}
}else{
?>