<?phpnamespace app\controllers;use yii\web\Controller;use yii\db\Connection;use Yii;class MyController extends Controller{    public function actionIndex()    {        $country = Yii::$app -> db -> createCommand("select * from country") -> queryAll();        print_r($country);    }}

<?phpreturn [    ‘class‘ => ‘yii\db\Connection‘,    ‘dsn‘ => ‘mysql:host=localhost;dbname=yii‘,    ‘username‘ => ‘root‘,    ‘password‘ => ‘12‘,    ‘charset‘ => ‘utf8‘,];