alunos.com.br/login.php

<?php
session_start ();
// include 'DAO/conection.php';
require_once 'init.php';

if (! empty ( $_POST )) {
    $user = $_POST ['user'];
    $password = $_POST ['password'];
    $has_cod = md5($password);
    try {

    //  $sql = ( "SELECT id, user, password From users where user=:user and password= :has_cod;" );
        $stmt = $pdo->prepare("SELECT user, password From users where user= :user and password= :has_cod;" );
        $stmt->bindParam ( ':user', $user, PDO::PARAM_STR );
        $stmt->bindParam ( ':has_cod', $has_cod, PDO::PARAM_STR);

        // Executa query
        $stmt->execute ();

        while ( $obj = $stmt->fetch ( PDO::FETCH_ASSOC ) ) {
            $obj {[
                    'id'
            ]};
            $obj {[
                    'user'
            ]};
        }

        if (empty ( $obj )) {
            echo "<script>alert('Seu login falhou. LOGIN: admin@admin.com SENHA: 1234');</script>";
        } else {
            $_SESSION ['logado'] = true;
            $_SESSION ['id'] = $obj ['id'];
            $_SESSION ['user'] = $obj ['user'];
            header ( "location: index.php" );
        }
    } catch ( PDOException $e ) {
        echo "Error: " . $e;
    }
}
?>


<!Doctype html>
<html lang="pt-br">
<head>
<title>Cadastro de Alunos</title>
<meta charset="utf8">
<!-- Chamada do CSS -->
<link rel="stylesheet" href="css/estilo.css">
<link rel="stylesheet" href="bootstrap/css/bootstrap.css">

<script src="bootstrap/js/jquery-1.12.4.min.js"></script>
<script src="bootstrap/js/bootstrap.min.js"></script>
</head>

<body>

    <form id="login" action="" method="post" class="panel panel-warning">

        <div class="panel-heading">
            <h3>Acesso Restrito - Faça seu login</h3>
        </div>

        <div class="panel-body">

            <div class="form-group">
                <label for="email">E-mail</label> <input type="text"
                    class="form-control" name="user" id="user"
                    placeholder="Digite seu e-mail de acesso" required autofocus>
            </div>


            <div class="form-group">
                <label for="senha">Senha</label>
                <input type="password"  class="form-control" name="password" id="password"   autocomplete="off" placeholder="Digite sua senha" required autofocus>
            </div>

            <div class="form-group">
                <input type="submit" class="btn btn-success" value="Acessar"  autocomplete="off"> <a href="" class="label label-warning" style="float: right;">Esqueci a senha!</a>
            </div>

        </div>
    </form>

</body>

</html>