submit_vote.php

<?php
include "connection.php";
session_start();
if (empty($_POST['lan'])) {
	$error = "<center><h4><font color='#FF0000'>Please select a language to vote!</h4></center></font>";
	include "voter.php";
	exit();
}
$lan = $_POST['lan'];
$sess = $_SESSION['SESS_NAME'];
$lan = addslashes($_POST['lan']);
$lan = mysqli_real_escape_string($con, $lan);
$sql = mysqli_query($con, 'SELECT * FROM voters WHERE username="' . $_SESSION['SESS_NAME'] . '" AND status="VOTED"');
if (mysqli_num_rows($sql) > 0) {
	$msg = "<center><h4><font color='#FF0000'>You have already been voted, No need to vote again</h4></center></font>";
	include 'voter.php';
	exit();
} else {
	$sql1 = mysqli_query($con, 'UPDATE languages SET votecount = votecount + 1 WHERE fullname = "' . $_POST['lan'] . '"');
	$sql2 = mysqli_query($con, 'UPDATE voters SET status="VOTED" WHERE username="' . $_SESSION['SESS_NAME'] . '"');
	$sql3 = mysqli_query($con, 'UPDATE voters SET voted= "' . $_POST['lan'] . '" WHERE username="' . $_SESSION['SESS_NAME'] . '"');
	if (!$sql1 && !$sql2) {
		die("Error on mysql query" . $mysqli -> error);
	} else {
		$msg = "<center><h4><font color='#FF0000'>Congratulation, you have made your vote.</h4></center></font>";
		include 'voter.php';
		exit();
	}
}