“智能"使用PDO和Memcache的缓存系统 [英] "Smart" Caching System using PDO and Memcache

问题描述

我正在开发一个使用pdo和memcache的智能"缓存系统.但是，我陷入了这个错误.你能帮我吗?

I am working on a "smart" caching system that uses pdo and memcache. However, I am stuck at this error. Can you help me out?

我的代码:

$session = "a121fd4ztr6";
cache_query("SELECT * FROM `session` WHERE `session` = :session: LIMIT 1;", array(':session:' => $session));

// CACHE QUERY
function cache_query($sql, $params) {
    global $db;
    global $memcache;

    $name = 'querycache-'.md5(serialize(array($sql, $params)));
    $result = $memcache->get($name);

    if (!$result) {
        if(!($db)){
            require("db.php");
        }

        $stmt = $db->prepare($sql);
        $exec = $stmt->execute($params);
        $result = $stmt->fetchAll(PDO::FETCH_ASSOC);

        $memcache->add($name, $result);
    }

    return $result;
}

db.php建立与PDO的连接. Memcache连接已建立.我总是收到以下错误:

db.php sets up a connection to PDO. Memcache connection is already set up. I always get the following error:

添加错误模式属性后，我现在得到了更详细的错误:

after adding the error mode attribute, I now get a more detailed error:

严重错误:消息为"SQLSTATE [42000]"的未捕获异常"PDOException":语法错误或访问冲突:1064您的SQL语法有错误；请参见表11.检查与您的MySQL服务器版本相对应的手册，以在/chroot/home/html/session.php:170

^这是怎么回事?

推荐答案

看起来像$db->prepare()返回错误，因此您的$stmt变量不是真正的PDOStatement对象.使用$db->errorInfo()查看出了什么问题.如果您已经设置了适当的属性，也可以将其放在try-catch块中(请参见

Looks like $db->prepare() returns an error, so your $stmt variable is not a real PDOStatement object. Use the $db->errorInfo() to see what's going wrong. You can also put it to a try-catch block, if you have set appropriate attributes (see Errors and error handling).

要查看连接是否正常，还可以使用try-catch:

To see if your connection is OK, you also can use try-catch:

try {
    $db = new PDO($dsn, $user, $password);
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
} catch (PDOException $e) {
    echo 'Connection failed: ' . $e->getMessage();
}

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