给定ID如何获取未知的用户名? [英] How can I get an unknown username given an ID?

问题描述

我得到了一个20个字符的数字ID，看起来像 10527391670258314752 ，给定了这个ID，我如何获得与之关联的用户名?

I got a numerical ID of 20 characters witch looks like 10527391670258314752, given this ID, how can I get the username associated with it?

该表如下所示:

id                   | name | password | balance   
10527391670258314752 | Jhon | 12345    | 12.51

从数据库中检索到的用户名应存储在$_SESSION['name']中.

The username retrieved from the database should then be stored into $_SESSION['name'].

我已经尝试过了:

$connection = mysqli_connect('localhost', 'root', '', 'user_data');
$id = '10527391670258314752';

$query = "SELECT username FROM user_data WHERE id = '$id'";
$result = mysqli_query($connection, $query);

$record = mysqli_fetch_array($id);
$_SESSION['id'] = $record;

echo $_SESSION['id'];

输出为Array()而不是名称.

推荐答案

我强烈建议您避免mysqli扩展.您应该使用一些数据库抽象库，而不是直接使用mysqli函数. mysqli类不适合单独使用.

I would strongly recommend to avoid mysqli extension. You should use some database abstraction library instead of using the mysqli functions directly. mysqli class is not suited to be used on its own.

如果您真的想使用纯mysqli类来做，则没有什么选择.

If you really want to do it with pure mysqli class, you have few options.

首先，您需要正确打开连接.这三行代码可确保您已做好连接准备:

First, you need to open the connection properly. These 3 lines ensure you have the connection ready:

mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT); // enable error reporting
$mysqli = new mysqli('localhost', 'username', 'password', 'dbname');
$mysqli->set_charset('utf8mb4'); // always set the charset

然后，您需要准备一条语句，绑定参数并执行它.

Then you need to prepare a statement, bind the parameter and execute it.

$id = '10527391670258314752';
$stmt = $mysqli->prepare('SELECT username FROM user_data WHERE id=?');
$stmt->bind_param('s', $id);
$stmt->execute();

执行语句后，您需要获取结果.如果只有一个变量，则可以简单地使用bind_result()

Once the statement is executed you need to fetch the results. If you have only one variable you could simply use bind_result()

$stmt->bind_result($_SESSION['name']);
$stmt->fetch();
echo $_SESSION['name'];

但是，不建议使用这种方法，也不是很灵活.相反，最好获取整个结果集并获取包含第一行的数组.

However, this approach is not recommended and not very flexible. Instead it's better to fetch the whole result set and get an array containing the first row.

$result = $stmt->get_result();
$row = $result->fetch_array();
$_SESSION['name'] = $row['username'];
echo $_SESSION['name'];

---

作为PDO的替代方案，相同的代码如下所示:

---

As an alternative with PDO the same code would look like this:

session_start();

$pdo = new PDO("mysql:host=$host;dbname=$db;charset=$charset", $user, $pass, [
    \PDO::ATTR_ERRMODE => \PDO::ERRMODE_EXCEPTION,
    \PDO::ATTR_EMULATE_PREPARES => false,
]);

$id = '10527391670258314752';

$stmt = $pdo->prepare('SELECT username FROM user_data WHERE id=?');
$stmt->execute([$id]);
$_SESSION['name'] = $stmt->fetchColumn();
echo $_SESSION['name'];

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