mySQLi 准备好的语句无法 get_result()

问题描述

我完全被 mySQLi 弄糊涂了.尽管我多年来一直在使用过程 mysql 调用，但我想习惯于为它提供的 db security/mySQL 注入保护制作准备好的语句.我正在尝试编写一个简单的选择语句(是的，我知道为此进行程序调用可提供性能增强).运行时，我得到所有回声，直到我点击 $result = $stmt->get_result(); 组件.这一切对我来说似乎相当简单，但在阅读了有关 mySQLi 的手册数小时后，我不知所措.任何想法为什么会失败?

I am totally confused by mySQLi. Although I have been using procedural mysql calls for years, I want to get used to making prepared statements for the db security/mySQL injection protection it offers. I am trying to write a simple select statement (yes I know making a procedural call for this offers performance enhancement). When run, I get all the echoes until I hit the $result = $stmt->get_result(); component. It all seems fairly straightforward to me, but I am at a loss after hours of reading manuals on mySQLi. Any ideas why this would be failing?

*注意:这是一个测试环境，虽然没有进行字符清理/转义，但我只是将有效内容传递到变量 $username 和 $email 中.而且，我已经查看了所有内容以找到我的问题的解决方案.

*note: this is a test environment and while no sanitizing/escaping of characters is taking place, I am only passing valid content into the variables $username and $email. And also, I have looked all over SO to find the solution to my issue.

function checkUsernameEmailAvailability($username, $email) {
    //Instantiate mysqli connection
    @$mysqli = new mysqli(C_HOST,C_USER,C_PASS,C_BASE) or die("Failed to connect to MySQL database...");
    if (!$mysqli)
    {
        echo 'Error: Could not connect to database.  Please try again later...';
        exit;
    } else {
        echo 'mysqli created';
    }

    /* Create a prepared statement */   
    if($stmt = $mysqli -> prepare("SELECT username,email FROM tb_users WHERE username=? OR email=?")) {
        echo '<br />MYSQLi: ';

        /* Bind parameters s - string, b - boolean, i - int, etc */
        $stmt -> bind_param("ss", $username, $email);
        echo '<br />paramsBound...';

        /* Execute it */
        $stmt -> execute();     
        echo '<br />Executed';

        $result = $stmt->get_result();
        echo '<br />Result acquired';

        /* now you can fetch the results into an array - NICE */
        $myrow = $result->fetch_assoc();
        echo '<br />Fetched';


        /* Close statement */
        /$stmt -> close();
        echo '<br />Done mysqli';
    }
}    

另外，每次调用函数时都必须实例化一个 mysqli 吗?我假设它们不是像程序 mysql 中那样的持久数据库连接.是的，我知道这是一个范围问题，不，我无法理解此类变量的范围.我在函数外声明的时候，进入函数时不可用.

Also, do I have to instantiate a mysqli every time I call a function? I'm assuming they're not persistent db connects like in procedural mysql. Yes, I am aware this is a scope issue, and no I have not been able to understand the scoping of this class variable. When I declared it outside of the function, it was not available when I came into the function.

更新如果我将第 12 行更改为:

UPDATE if I change line 12 from:

if($stmt = $mysqli -> prepare("SELECT username,email FROM tb_users WHERE username=? OR email=?")) {

到:

    $stmt = $mysqli->stmt_init();
    if($stmt = $mysqli -> prepare("SELECT username,email FROM tb_users WHERE username=? OR email=?")) {
        if(!stmt) echo 'Statement prepared'; else echo 'Statement NOT prepared';

我没有准备好声明.现在我更糊涂了....

I get Statement NOT prepared. Now I'm even more confused....

更新:我联系了我的托管服务提供商，显然支持 mySQLi，并且存在 mysqlnd 驱动程序.也许有一种方法可以简单地测试这个?尽管过去他们通常会给我非常有见地的答案.

UPDATE: I contacted my hosting provider and apparently mySQLi is supported, and the mysqlnd driver is present. Perhaps there is a way to simply test this? Although they usually have given me pretty knowledgeable answers in the past.

更新...再次:我自己检查了我的服务器功能并发现，虽然存在 mysqli 和 PDO，但 mysqlnd 不存在.因此，我明白为什么 get_result() 不起作用(我认为需要 mysqlnd)，我仍然不明白为什么准备好的语句本身不起作用.

UPDATE...AGAIN: I checked my server capabilities myself and discovered, while mysqli and PDO are present, mysqlnd is not. Thusly, I understand why get_result() will not work (mysqlnd required I think), I still don't understand why the prepared statement itself will not work.

推荐答案

通过一些检查，尽管我的主机上安装了 mysqli，但显然 mysqlnd 驱动程序不存在.因此，无法使用 get_result()(php 手册将 get_result 定义为依赖于 mysqlnd)，而是需要进行额外的编码以按照我想要的方式处理我的结果.

Through some checking, even though mysqli is installed on my host, apparently the mysqlnd driver is not present. Therefore, get_result() can not be used(php manual defines get_result as mysqlnd dependent), and instead extra coding would need to be done to handle my result the way I would like.

因此，我决定尝试了解 PDO 的工作原理，几分钟之内，瞧！！！

Therefore, I decided to try and learn how PDO works, and within minutes, voila!!!

用这个替换上面的代码:

Replaced the above code with this:

function checkUsernameEmailAvailability($username, $email) {

echo 'pdo about to be created';

$dsn = 'mysql:dbname='.C_BASE.';host='.C_HOST;
$user = C_USER;
$password = C_PASS;

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

$params = array(':username' => $username, ':email' => $email);

try{
$sth = $dbh->prepare('SELECT username,email FROM tb_users WHERE username = :username OR email = :email ');
} catch(PDOException $e) {
    echo 'Prepare failed: ' . $e->getMessage();
}

try{
$sth->execute($params);
} catch(PDOException $e) {
    echo 'Execute failed: ' . $e->getMessage();
}
$result = $sth->fetch(PDO::FETCH_ASSOC);
print_r($result);
}

我能想到的尽可能多的错误检查，首先破解它根本没有问题！

As much error checking as I could think of, and no problems at all first crack at it!

最终代码

function checkUsernameEmailAvailability($username, $email) {
    $dsn = 'mysql:dbname='.C_BASE.';host='.C_HOST;
    $user = C_USER;
    $password = C_PASS;
    new PDO($dsn, $user, $password);

    $params = array(':username' => $username, ':email' => $email);

    $sth = $dbh->prepare('SELECT username,email FROM tb_users WHERE username = :username OR email = :email ');
    $sth->execute($params);
    $result = $sth->fetch(PDO::FETCH_ASSOC);

    print_r($result);
}

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