要在两个数据库实例（同一个server）上进行关联数据查询，纯SQL语句如下：

select a.*,b.* from db1.user as a,db2.log as b where a.id=b.user_id;

要在Yii1 Model中支持这个，需要修改下user模型类的getDbConnection和tableName方法如下：

	/**
	 * @return CDbConnection database connection
	 */
	public function getDbConnection()
	{
		return Yii::app()->db_log;
	}

	/**
	 * @return string the associated database table name
	 */
	public function tableName()
	{
        preg_match("/dbname=([^;]+)/i", $this->dbConnection->connectionString, $matches);
        return $matches[1].'.log';
	}