Yii CDbConnection无法打开数据库连接

Question

I'm trying to enter Model Generator and Crud Generator, but it gives this Database(MYSQL) connection error. I searched on the internet but couldn't find working solution. Hope you can help me. I'm using Netbeans IDE. Thanks in advance.

Note: I can connect the database without using Yii.

CDbConnection failed to open the DB connection: could not find driver

L:\WT-NMP\WWW\yii-1.1.15.022a51\framework\gii\generators\crud\CrudCode.php(44)

 public function requiredTemplates()
 {
     return array(
        'controller.php',
    );
 }

 public function init()
 {
     if(Yii::app()->db===null)
         throw new CHttpException(500,'An active "db" connection is required to run this generator.');
     parent::init();
 }

public function successMessage()
 {
     $link=CHtml::link('try it now', Yii::app()->createUrl($this->controller), array('target'=>'_blank'));
     return "The controller has been generated successfully. You may $link.";
 }

 public function validateModel($attribute,$params)
 {

  //...............................

And Here is the main.php

  <?php

// uncomment the following to define a path alias
// Yii::setPathOfAlias('local','path/to/local-folder');

// This is the main Web application configuration. Any writable
// CWebApplication properties can be configured here.
return array(
'basePath'=>dirname(__FILE__).DIRECTORY_SEPARATOR.'..',
'name'=>'My Web Application',

// preloading 'log' component
'preload'=>array('log'),

// autoloading model and component classes
'import'=>array(
    'application.models.*',
    'application.components.*',
),

'modules'=>array(
    // uncomment the following to enable the Gii tool

    'gii'=>array(
        'class'=>'system.gii.GiiModule',
        'password'=>'pass',
        // If removed, Gii defaults to localhost only. Edit carefully to taste.
        'ipFilters'=>array('127.0.0.1','::1'),
    ),

),

// application components
'components'=>array(
    'user'=>array(
        // enable cookie-based authentication
        'allowAutoLogin'=>true,
    ),
    // uncomment the following to enable URLs in path-format
    /*
    'urlManager'=>array(
        'urlFormat'=>'path',
        'rules'=>array(
            '<controller:\w+>/<id:\d+>'=>'<controller>/view',
            '<controller:\w+>/<action:\w+>/<id:\d+>'=>'<controller>/<action>',
            '<controller:\w+>/<action:\w+>'=>'<controller>/<action>',
        ),
    ),
    */
//      'db'=>array(
//          'connectionString' => 'sqlite:'.dirname(__FILE__).'/../data/testdrive.db',
//      ),
    // uncomment the following to use a MySQL database

    'db'=>array(
        'connectionString' => 'mysql:host=localhost;dbname=yii',
        'emulatePrepare' => true,
        'username' => 'root',
        'password' => '',
        'charset' => 'utf8',
                    'tablePrefix' => 'tbl ',
    ),

    'errorHandler'=>array(
        // use 'site/error' action to display errors
        'errorAction'=>'site/error',
    ),
    'log'=>array(
        'class'=>'CLogRouter',
        'routes'=>array(
            array(
                'class'=>'CFileLogRoute',
                'levels'=>'error, warning',
            ),
            // uncomment the following to show log messages on web pages
            /*
            array(
                'class'=>'CWebLogRoute',
            ),
            */
        ),
    ),
),

// application-level parameters that can be accessed
// using Yii::app()->params['paramName']
'params'=>array(
    // this is used in contact page
    'adminEmail'=>'[e-mail]',
),
);