Users Level Login System Leads to Blank Page

lybat · August 13, 2013

I'm creating a users level login system in php & mysql. However, it leads to a white blank page. I can't figure the error. Any help is much appreciated. Thanks.

Form.html

<!DOCTYPE html>



 <html lang="en"> 
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge,chrome=1">
<title>MIS Electronic Request</title>
<link rel="stylesheet" href="css/style.css">

</head>
<body>
<br>

<form method="post" action="main.php" class="login">
    <p>
      <label for="login">Username:</label>
      <input type="text" name="myusername" id="myusername" value="Employee id">
    </p>

    <p>
      <label for="password">Password:</label>
      <input type="password" name="mypassword" id="mypassword" value="4815162342">
    </p>

    <p class="login-submit">
      <button type="submit" class="login-button">Login</button>
    </p>

</form>

</body>
</html>

Main.php

<?php
session_start();
$host="localhost";
$username="root";
$password="******";
$db_name="htdocs";
$tbl_name="users";

mysql_connect("$host", "$username", "$password")or die("Unable to connect to MySQL: " . mysql_error());
mysql_select_db("$db_name")or die("Unable to select database: " . mysql_error());

if (isset($_POST['submit']))
{
// username and password sent from form
$myusername=$_POST['myusername'];
$mypassword=$_POST['mypassword'];

$myusername = stripslashes($myusername);
$mypassword = stripslashes($mypassword);
$myusername = mysql_real_escape_string($myusername);
$mypassword = mysql_real_escape_string($mypassword);

$sql="SELECT * FROM $tbl_name WHERE username='$myusername' and password='$mypassword'";
$result=mysql_query($sql);

// Mysql_num_row is counting table row
$count=mysql_num_rows($result);

if($count==1){
   if (user_level == 1) {
        $_SESSION['myusername'] = $myusername;
        $_SESSION['mypassword'] = $mypassword;
        header("Location:Admin_home.php");
        }
   else if (user_level == 2) {
        $_SESSION['myusername'] = $myusername;
        $_SESSION['mypassword'] = $mypassword;
        header("Location:home.php");
   }
}
else {
echo "Wrong Username or Password";
}
}

?>

davidannis · August 13, 2013

try adding name="submit" to the submit button or check like this:

if (isset($_POST['myusername']) || isset($_POST['mypassword']))

lybat · August 13, 2013

Thanks for the reply. The blank page issue has been resolved. But this time i got this error:

Error:

Notice: Use of undefined constant user_level - assumed 'user_level' in C:\wamp\www\htdocs\main.php on line 34

Notice: Use of undefined constant user_level - assumed 'user_level' in C:\wamp\www\htdocs\main.php on line 39

PaulRyan · August 13, 2013

You have missed the $ off both the following lines.

if (user_level == 1) {

if (user_level == 2) {

lybat · August 14, 2013

Hi i already did that. still error..

if($count==1){
   if ($user_level == 1) {
        $_SESSION['myusername'] = $myusername;
        $_SESSION['mypassword'] = $mypassword;
        header("Location:Admin_home.php");
        }
   else if ($user_level == 2) {
        $_SESSION['myusername'] = $myusername;
        $_SESSION['mypassword'] = $mypassword;
        header("Location:home.php");
   }
}

PaulRyan · August 14, 2013

You have updated the wrong file then, my suggestion would fix the 2 "Use of undefined constant" errors.

davidannis · August 14, 2013

and you still should have a space after Location:

header("Location:Admin_home.php");

 header("Location:home.php");

but you don't need the space in else if you can use elseif

PaulRyan · August 14, 2013

and you still should have a space after Location:
header("Location:Admin_home.php");
 header("Location:home.php");
but you don't need the space in else if you can use elseif

You don't need the space after "Location:", if you had tried it, you would see it works without the space.

mac_gyver · August 14, 2013

the error message probably did change to an undefined variable message.

the php variable $user_level is not defined anywhere in the posted code. where do you expect it to get its value from and where is your code setting it to that value?

davidannis · August 14, 2013

Good catch Mac-gyver. The record is never fetched. I bet the OP is looking for something like $row['user_level'] from the database row that never got fetched.

lybat · August 15, 2013

Guys, thanks for all the comment. How can i defined or fetched the value of user_level from the database?

user_level = $row['user_level']

is this correct?

mac_gyver · August 15, 2013

no, it's not correct.

i recommend that you read a php/mysql book or tutorial as you are currently not aware of even the syntax for a php variable and you will also need to know how to fetch a row from the result set that a query returns.

davidannis · August 15, 2013

You don't need the space after "Location:", if you had tried it, you would see it works without the space.

You are right. The space is is ignored and multiple spaces after the colon should work too (according to the RFC). I thought I had an issue a few moths ago that I solved by adding a space after the colon in a header, but I must be remembering it incorrectly. I stand corrected. Sorry.

lybat · August 22, 2013

still can't figure it out until now.. any help? Thanks!

mac_gyver · August 22, 2013

do you still have a problem or error with your code after all this time? you should probably post your current code as well.

Twysted · August 22, 2013

still can't figure it out until now.. any help?

after this

$count=mysql_num_rows($result);

add this

$row=mysql_fetch_array($result);

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Users Level Login System Leads to Blank Page

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