yii-user-management安装时出错 [ 新手入门 ]

使用的是：yii-user-management_0.8rc6.tar.bz2 安装时，会报错：

CDbCommand failed to execute the SQL statement: SQLSTATE[HY000]: General error: 2014 Cannot execute queries while other unbuffered queries are active. Consider using PDOStatement::fetchAll(). Alternatively, if your code is only ever going to run against mysql, you may enable query buffering by setting the PDO::MYSQL_ATTR_USE_BUFFERED_QUERY attribute.. The SQL statement executed was: CREATE TABLE IF NOT EXISTS `user_group` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`owner_id` int(11) NOT NULL,
`participants` text NULL,
`title` varchar(255) NOT NULL,
`description` text NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

我使用Yii::app()->db->setAttribute(PDO::MYSQL_ATTR_USE_BUFFERED_QUERY, true)后，会报错： Database connection is not working