http://blog.csdn.net/jake451/article/details/6117272

引用

http://blog.csdn.net/jake451/article/details/6117272

需求：原网站功能庞大，数据库服务器与数据库众多



问题：YII单DB方式已经满足不了我们的需求，急切需要对YII进行扩展设计，支持多DB方式



解决方法：

1、在protected/components目录下新建Ar.php脚本文件。
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01.<?php 
02.class Ar extends CActiveRecord 
03.{ 
04.    static $database = array(); 
05.    public $dbname  = 'db'; 
06.    public function __construct($scenario='insert', $dbname = '') 
07.    { 
08.        if (!emptyempty($dbname)) 
09.            $this->dbname    = $dbname; 
10.             
11.        parent::__construct($scenario); 
12.    } 
13.     
14.    public function getDbConnection() 
15.    { 
16.        $dbname = $this->dbname; 
17.        if (self::$database[$dbname]!==null) 
18.        { 
19.            return self::$database[$dbname]; 
20.        } 
21.        else 
22.        { 
23.            if ($this->dbname == 'db') 
24.            { 
25.                self::$database[$dbname] = Yii::app()->getDb(); 
26.            } 
27.            else  
28.            { 
29.                self::$database[$dbname] = Yii::app()->$dbname; 
30.            } 
31.                 
32.            if(self::$database[$dbname] instanceof CDbConnection) 
33.            { 
34.                self::$database[$dbname]->setActive(true); 
35.                return self::$database[$dbname]; 
36.            } 
37.            else 
38.                throw new CDbException(Yii::t('yii','Active Record requires a "db" CDbConnection application component.')); 
39.        } 
40.    } 
41.} 
<?php
class Ar extends CActiveRecord
{
static $database = array();
public $dbname = 'db';
public function __construct($scenario='insert', $dbname = '')
{
if (!empty($dbname))
$this->dbname = $dbname;

parent::__construct($scenario);
}

public function getDbConnection()
{
$dbname = $this->dbname;
if (self::$database[$dbname]!==null)
{
return self::$database[$dbname];
}
else
{
if ($this->dbname == 'db')
{
self::$database[$dbname] = Yii::app()->getDb();
}
else
{
self::$database[$dbname] = Yii::app()->$dbname;
}

if(self::$database[$dbname] instanceof CDbConnection)
{
self::$database[$dbname]->setActive(true);
return self::$database[$dbname];
}
else
throw new CDbException(Yii::t('yii','Active Record requires a "db" CDbConnection application component.'));
}
}
}

2、数据库配置

     为了方便与清晰我们的数据库配置文件，我们将数据库配置文件与main.php文件进行分离。



     （1）首先我们看看main.php文件的配置，代码如下

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01.<?php 
02.$config = array( 
03.    'basePath'=>dirname(__FILE__).DIRECTORY_SEPARATOR.'..', 
04.    'name'=>'My Web Application', 
05.         //...此处代码已省略，去掉components里面的db文件配置  
06.    ); 
07. 
08.$database   = @include_once dirname(__FILE__).'/database.php'; 
09.if(!emptyempty($database)) 
10.{ 
11.    $config['components'] = @array_merge($config['components'], $database); 
12.} 
13.return $config; 
<?php
$config = array(
'basePath'=>dirname(__FILE__).DIRECTORY_SEPARATOR.'..',
'name'=>'My Web Application',
         //...此处代码已省略，去掉components里面的db文件配置
);

$database = @include_once dirname(__FILE__).'/database.php';
if(!empty($database))
{
$config['components'] = @array_merge($config['components'], $database);
}
return $config;

    （2）在配置文件目录(protected/config)，新建database.php脚本文件，代码如下

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01.<?php 
02.return array( 
03.    /** 默认数据库 */ 
04.    'db'=>array( 
05.            'connectionString' => 'dblib:host=test;dbname=test', 
06.            'emulatePrepare' => false, 
07.            'username' => 'user', 
08.            'password' => 'pass', 
09.            'charset' => 'gbk', 
10.    ), 
11.    /** mysql配置 */   
12.    /*'shop'=>array(
13.            'connectionString' => 'mysql:host=mysql.data.com;dbname=test1',
14.            'emulatePrepare' => true,
15.            'username' => 'root',
16.            'password' => '123456',
17.            'charset' => 'utf8',
18.            'tablePrefix' => '',
19.        ),*/ 
20.         
21.    /** mssql配置 */ 
22.    'test1'=>array( 
23.            'connectionString' => 'dblib:host=testHostname;dbname=test1', 
24.            'emulatePrepare' => false, 
25.            'username' => 'user', 
26.            'password' => 'pass', 
27.            'charset' => 'gbk', 
28.        ),); 
<?php
return array(
/** 默认数据库 */
'db'=>array(
'connectionString' => 'dblib:host=test;dbname=test',
'emulatePrepare' => false,
'username' => 'user',
'password' => 'pass',
'charset' => 'gbk',
),
/** mysql配置 */
/*'shop'=>array(
'connectionString' => 'mysql:host=mysql.data.com;dbname=test1',
'emulatePrepare' => true,
'username' => 'root',
'password' => '123456',
'charset' => 'utf8',
    'tablePrefix' => '',
),*/

/** mssql配置 */
'test1'=>array(
'connectionString' => 'dblib:host=testHostname;dbname=test1',
'emulatePrepare' => false,
'username' => 'user',
'password' => 'pass',
'charset' => 'gbk',
),);



    （3）在使用的时候，我们需要对model文件进行简单的修改。

           a、将继承文件类换成Ar

           b、给model添加属性$dbname设置所在数据库配置文件名称(不设置则为默认DB)

           实例代码如下：

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01.<?php 
02.class test extends Ar 
03.{ 
04.    //设置处理所在数据库，不设置为默认DB  
05.    $dbname = 'test1'; 
06.    //...省略代码若干行  
07.}