yii2连接数据库失败

    public function actionIndex()
    {
        $query = Country::find();
 
        $pagination = new Pagination([
            'defaultPageSize' => 5,
            'totalCount' => $query->count()
        ]);
 
        $countries = $query->orderBy('name')
            ->offset($pagination->offset)
            ->limit($pagination->limit)
            ->all();
 
        return $this->render('index', [
            'countries' => $countries,
            'pagination' => $pagination,
        ]);
    }

<?php
 
return [
    'class' => 'yii\db\Connection',
    'dsn' => 'mysql:host=localhost;dbname=yii2basic',
    'username' => 'root',
    'password' => '',
    'charset' => 'utf8',
 
    // Schema cache options (for production environment)
    //'enableSchemaCache' => true,
    //'schemaCacheDuration' => 60,
    //'schemaCache' => 'cache',
];

<?php
 
return [
    'class' => 'yii\db\Connection',
    'dsn' => 'mysql:host=127.0.0.1;dbname=yii2basic',
    'username' => 'root',
    'password' => '',
    'charset' => 'utf8',
 
    // Schema cache options (for production environment)
    //'enableSchemaCache' => true,
    //'schemaCacheDuration' => 60,
    //'schemaCache' => 'cache',
];