Cannot register registered username

App/Controllers/Home.php

@@ -71,6 +71,15 @@ class Home
         $args['full_name'] = htmlspecialchars($args['full_name']);
         $args['username'] = htmlspecialchars($args['username']);
 
+        $data = $this->access->showAll();
+        foreach ($data as $users) {
+            if ($args['username'] == $users['username']) {
+                Session::flash('info', 'Username already exists');
+                Redirect::to('./register');
+                die();
+            }
+        }
+
         $this->access->entry($table, $args);
 
         Redirect::to('/');

App/Models/Access.php

@@ -30,7 +30,7 @@ class Access extends \Core\Model
 
             if ($stmt = $db->query($sql)) {
                 $result = $stmt->fetchAll(\PDO::FETCH_ASSOC);
-                return true;
+                return $result;
             }
             return false;
         } catch (PDOException $e) {