php - Slim framework project error -

i've created new project:

project tree can see @ right of screen , database @ left.

my home.php file:

<?php  $app->get('/',function() use($app) {      $posts = $app->db->query("         select         posts.*         posts         left join users         on posts.pauthor = users.id;     ")->fetchall(pdo::fetch_assoc);      var_dump($posts);     die();  })->name('home'); 

my index.html file:

<?php      require '../app/start.php'; 

my routes.php file:

<?php      require 'routes/home.php'; 

my start.php(main app file):

<?php  require '../vendor/autoload.php';  $app = new \slim\slim(); //    database $app->container->singleton('db',function(){     return new pdo('mysql:127.0.0.1;dbname=blog','root',''); });  require 'routes.php';  $app->run(); 

and after trying open project had error occured:

is there wrong? i'm following lesson: https://www.youtube.com/watch?v=srfygco3xo4(not pr).

is there wrong?

yes. if copy-paste something, right.. forgot host while initialize pdo.

$app->container->singleton('db',function(){     return new pdo('mysql:host=127.0.0.1;dbname=blog','root',''); });