How To Fix CDbConnection failed to open the DB connection could not find driver on Yii Mysql

•  Make sure  your PHP engine location path in system variable.
•  Make sure you active php_pdo_mysql on php.ini

If your error in web

Uncomment the following to use a MySQL database on protection/config/main.php

                               

'db'=>array(

'connectionString' => 'mysql:host=localhost;dbname=yiidb',

'emulatePrepare' => true,

'username' => 'root',

'password' => 'your pass',

'charset' => 'utf8',

),

                If your error in console

                 Uncomment the following to use a MySQL database protection/config/console.php     

'db'=>array(

'connectionString' => 'mysql:host=localhost;dbname=yiidb',

'emulatePrepare' => true,

'username' => 'root',

'password' => 'your pass',

'charset' => 'utf8',

),

 You can change host with 127.0.0.1 

Have Nice Day