一般错误:1 Can'；t创建/写入文件错误代码:2

我正试图将CSV文件写入/var/www/VistaMind_CMStmp，但收到错误消息：SQLSTATE[HY000]: General error: 1 Can't create/write to file '/VistaMind_CMS/tmp/app_users.csv' (Errcode: 2)

我试过做chown mysql:mysql /var/www/VistaMind_CMS/tmp，但不起作用。我不想修改my.cnf中的TMPDIR var，它目前设置为/var/www，但我希望MySQL将数据库表转储到/var/www/VistaMind_CMS/tmp。

请帮忙！

我的代码是：

    $file_path = $this->view->baseUrl()."/../tmp/app_users.csv";
    $sql = "SELECT * FROM users INTO OUTFILE '".$file_path."' ".
            "FIELDS TERMINATED BY ','
            ENCLOSED BY ''"'
            LINES TERMINATED BY ''n'";
    $db = Zend_Registry::get('db');
    $stmt = $db->query($sql, array());
    echo "Done!!";