vote_function

<?php
session_start();
$vp = $_POST['vp'];

if(isset($_POST['votetest'])) {
    $vote_last_time = "SELECT vote_time FROM vote_cooldown WHERE account = '" . $_SESSION['username'] . "'";
    if($vote_last_time >= time() - 60 * 60 * 12) {
    $new_time = "UPDATE `vote_cooldown` SET vote_time=now() WHERE account = '" . $_SESSION['username'] . "'";
    $addvp = "UPDATE auth.account SET vp = vp+$vp WHERE account = '" . $_SESSION['username'] . "'";
    } else {
        echo "You can't vote now";
    }
}else{
    echo "Button have not been clicked";
}