Yii MySQL modifies database data

<?<span>php
    </span><span>/*</span><span>     * $id 代表主键，可以是一个也可以是一个集合。
      * $attributes 代表是要修改的字段的集合。
      * $condition 代表条件。
      * $params 传入的值。
      </span><span>*/</span><span>$count</span> = Model::model()->updateByPk(<span>$id</span>,<span>$attributes</span>,<span>$condition</span>,<span>$params</span><span>);
    </span><span>if</span>(<span>$count</span> > 0<span>) {
        </span><span>echo</span> '修改成功'<span>;
    } </span><span>else</span><span> {
        </span><span>echo</span> '修改失败'<span>;
    }
</span>?>

<?<span>php
    </span><span>$model</span> = Model::model()->findByPk(<span>$id</span><span>);
    </span><span>$model</span>->username = 'yiistudy'<span>;
    </span><span>$model</span>->password = 'mysql'<span>;
    </span><span>$count</span> = <span>$model</span>->update(<span>array</span>('username','password'<span>));
    </span><span>if</span>(<span>$count</span>>0<span>) {
        </span><span>echo</span> '修改成功'<span>;
    } </span><span>else</span><span> {
        </span><span>echo</span> '修改失败'<span>;
    }
</span>?>