php利用session 用户登陆教程

  if($_POST[submit]){
    $username= str_replace(" ","",$_POST[username]);
    $sql="select * from user_list where `username` = '$username'";
    $query=mysql教程_query($sql);
    $us=is_array($row=mysql_fetch_array($query));
    $ps教程= $us ? md5($_POST[password].ALL_PS)== $row[password] : FALSE;
    $pw=$ps?$_SESSION["code"]==$_POST[code]:FALSE;

    if($ps){
     $_SESSION[uid]=$row[uid];
     $_SESSION[user_shell]=md5($row[username].$row[password].ALL_PS);
        $_SESSION[times]=mktime();

        if($pw){
     echo "登陆成功";
     }
     else{
      echo "验证码错误";
      session_destroy();
     }
    }else{

        echo "密码或者用户名错误";
         session_destroy();
    }

  }

?>

CREATE TABLE `user_list` (
  `uid` int(11) NOT NULL auto_increment,
  `m_id` varchar(5) NOT NULL,
  `username` varchar(25) NOT NULL,
  `password` varchar(64) NOT NULL,
  PRIMARY KEY  (`uid`)
) ENGINE=MyISAM  DEFAULT CHARSET=gb2312 AUTO_INCREMENT=11 ;

--
-- 导出表中的数据 `user_list`
--

INSERT INTO `user_list` (`uid`, `m_id`, `username`, `password`) VALUES
(9, '1', 'admin', '75cf565ad38d0f837c43363e402b1a00'),
(10, '2', 'admin2', '75cf565ad38d0f837c43363e402b1a00');