Regristro.php

<?php
session_start();

if(isset($_POST['email']) && empty($_POST['email']) == false) {
    $nome = addslashes($_POST['nome']);
    $email = addslashes($_POST['email']);
    $senha = md5(addslashes($_POST['senha']));


    $dsn = "mysql:dbname=crypto;host: 127.0.0.1;";
    $dbuser = "root";
    $dbpass = "";

    $db = new PDO($dsn, $dbuser, $dbpass);

    try {
        $stmt = $db->prepare('INSERT INTO users (nome, email, senha) VALUES (:nome,:email, :senha)');
        $stmt->execute(array(
            ':nome' => $nome,
            ':email' => $email,
            ':senha' => $senha
        ));

        $sql = $db->query("SELECT * FROM users WHERE email = '$email'");

        if($sql->rowCount()  > 0) {
            $_SESSION['emailexiste'] = 1;
        }elseif ($sql->rowCount()  < 1) {
            $_SESSION['emailexiste'] = 0;


            $sql = $db->query("SELECT * FROM users WHERE email = '$email' AND senha = '$senha'");


            if ($sql->rowCount() > 0) {

                $dado = $sql->fetch();

                $_SESSION['id'] = $dado['id'];
                $nome = $dado['nome'];
                $_SESSION['email'] = $dado['email'];

                $array = explode(" ", $nome);
                $_SESSION['nome'] = $array[0];

                header("Location: index.php");

            }

        }elseif ($email == '') {
            $_SESSION['emailexiste'] = null;

        }


    } catch
    (PDOException $e) {
        echo "Falhou: " . $e->getMessage();
    };

};