防止sql注入的方法 php

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

try {
    // 创建PDO连接
    $conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
    // 设置PDO错误模式为异常
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // 准备SQL语句
    $stmt = $conn->prepare("SELECT * FROM users WHERE username = :username AND password = :password");
    
    // 绑定参数
    $stmt->bindParam(':username', $username);
    $stmt->bindParam(':password', $password);

    // 设置参数并执行
    $username = "admin";
    $password = "password123";
    $stmt->execute();

    // 获取结果
    $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
    print_r($result);

} catch(PDOException $e) {
    echo "Error: " . $e->getMessage();
}

$conn = null;
?>