login.php

<?php
    if(isset($_POST['name']) && !isset($display_case)){
        $name=htmlspecialchars($_POST['name']);
        $sql=$dbh->prepare("SELECT name FROM chatters WHERE name=?");
        $sql->execute(array($name));

        if($sql->rowCount()!=0 || $_POST['name'] == ""){
           $ermsg="<div class='error'>Nama sudah terpakai. Coba gunakan nama yang lain.</div>";
        }else{
           $sql=$dbh->prepare("INSERT INTO chatters (name,seen) VALUES (?,NOW())");
           $sql->execute(array($name));
            $_SESSION['user']=$name;
        }
    } elseif(isset($display_case)){
        if(!isset($ermsg)){
?>
        <form action="index.php" method="POST">
            <input name="name" class="feedback-input" placeholder="Masukan nama user" required/>
            <button id="button-blue">Masuk</button>
        </form>
<?php
        }else{
?>
        <form action="index.php" method="POST">
            <input name="name" class="feedback-input" placeholder="Masukan nama user" required/>
            <button id="button-blue">Masuk</button>
        </form>
<?php
         echo $ermsg;
        }
    }
?>
<footer>Meganeko's Blog</footer>