问题代码

1，控制器代码如下：

    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,
        ]);
    }

2，数据库配置文件db.php代码如下：

 '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',
];

3，问题截图：

解决办法

将PDO连接中的dsn的host由“localhost”改为“127.0.0.1”即可，打开文件DB.PHP，修改如下：

 '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',
];

结果截图