我的登录页面无法正常工作

Question

我正在尝试制作登录页面。我将一些数据存储在数据库中。当我输入数据然后它将显示我不知道y即将到来的错误，因为我定义索引.....

php code

  

  //var_dump($_POST);
  // Grab User submitted information


  $user = $_POST["username"];
  $pass = $_POST["password"];

  if(empty($user) && empty($pass))
  {

      $msg = "Pleae enter username and password";
  }
  else
  {
  // Connect to the database
  $con = mysql_connect("localhost","root","","jj");
  // Make sure we connected succesfully
  if(! $con)
  {
      session_start();
  $_SESSION['Logged in'] = true;
      die('Connection Failed'.mysql_error());
  }

  // Select the database to use
  mysql_select_db("jj");

  $qry = "SELECT username, password FROM login WHERE username = '".$user."' and password = '".$pass."'";
  echo $qry;


  $result = mysql_query($qry);

  //var_dump($result);
  $row = mysql_fetch_array($result);



  //var_dump($row);  //check the row 
  if($row["username"]==$user && $row["password"]==$pass)
      {
          $msg = "You are a validated user.";


          session_start();

          $_SESSION['username'] = $row["username"];

          $_SESSION['logged_in'] = true;

          header("Location: Iphoneunlockingcenter.html");
          die();
      }
  else
      {
          $msg ="Sorry, your credentials are not valid, Please try again.";
      }


  }
  }

?>

当我尝试登录时，错误来了 图片正在显示

Answer 1

你必须使用ISSET。

尝试替换此

  $user = $_POST["username"];
  $pass = $_POST["password"];

通过

  if(isset($_POST["username"]) and isset($_POST["password"])){
    $user = mysql_real_escape_string($_POST["username"]); //escape your variables
    $pass = mysql_real_escape_string($_POST["password"]);
     }
   else {
      $user = '';
      $pass = '';
   }