在 Yii2

最有可能是你的系统配置.如果你使用的是像这样的包MAMP、XAMPP 或其他，您可能需要将localhost"更改为db.php 配置文件中的127.0.0.1".另外如果你在Linux 你可能需要安装一些其他的附加包，比如php5-mysql 之类的东西."

"Most likely it is your system config. If you are using packages like MAMP, XAMPP or other, you may need to change "localhost" to "127.0.0.1" in your db.php configuration file. Also if you are on Linux you may need to install some other additional packages like php5-mysql and stuff like that."