Notice: Undefined index: SESS_NAME in student_vote.php on line 9 - php

Question

<?php
include "connection.php";
if(!isset($_SESSION))
{
session_start();
}
$cand1 = $_POST['cand1'];
$cand2 = $_POST['vice1'];
$sess = $_SESSION['SESS_NAME'];
if(!$cand1){
$error="<center><h4><font color='#FF0000'>Please fill empty fields</h4></center></font>";
include"student.php";
exit();
}
$cand1 = addslashes($cand1);
$cand1 = mysqli_real_escape_string($con,$cand1);
$sql = 'SELECT * FROM student WHERE username="'.$_SESSION['SESS_NAME'].'" AND status="VOTED"';
$result = mysqli_query($con,$sql);
if (mysqli_num_rows($result)==1){
$msg="<center><h4><font color='#FF0000'>You have already been voted, No need to vote again</h4></center></font>";
include 'student.php';
exit();
}
else{
$sql = 'UPDATE candidate SET votecount = votecount + 1 WHERE cand_id = "'.$_POST['cand1'].'" OR cand_id = "'.$_POST['vice1'].'"';
$sql2 = 'UPDATE student SET status="VOTED" WHERE username="'.$_SESSION['SESS_NAME'].'"';
$result = mysqli_query($con,$sql);
$result2 = mysqli_query($con,$sql2);
if(!$result && !$result2){
die("Error on mysql query".mysqli_error());
}
else{
$msg="<center><h4><font color='#FF0000'>Congratulation, you have made your vote.</h4></center></font>";
include 'student.php';
exit();
}
}
?>
the errors are at code including
$sess= $_SESSION['SESS_NAME']; and at username="'.$_SESSION['SESS_NAME'].'"
i have tried every possibility so can you check my code?
mainly the error is undefined index at $session[session_name]?

Answer 1

Are you sure the session 'SESS_NAME' is getting set? In the code above you are only trying to access its value. Undefined index is the error thrown when there is no session with that name.

Answer 2

Looks like to me you haven't declared the variable $_SESSION['SESS_NAME']. Try doing the following
var_dump($_SESSION);
This will show you all the defined variables in the session, if SESS_NAME isn't there then it hasn't been defined. Maybe you have failed to define it somewhere else?