<?php
// 创建数据库连接
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

$conn = new mysqli($servername, $username, $password, $dbname);

// 检查连接
if ($conn->connect_error) {
    die("连接失败: " . $conn->connect_error);
}

// 准备SQL语句
$sql = "DELETE FROM users WHERE id=3";

// 执行查询
if ($conn->query($sql) === TRUE) {
    echo "记录删除成功";
} else {
    echo "错误: " . $sql . "<br>" . $conn->error;
}

// 关闭连接
$conn->close();
?>

<?php
try {
    // 创建PDO连接
    $conn = new PDO("mysql:host=localhost;dbname=myDB", "username", "password");
    // 设置PDO错误模式为异常
    $conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
    
    // 准备SQL语句并使用参数绑定
    $stmt = $conn->prepare("DELETE FROM users WHERE id=:id");
    $stmt->bindParam(':id', $id);
    
    // 设置参数并执行
    $id = 3;
    $stmt->execute();
    
    echo "记录删除成功";
}
catch(PDOException $e) {
    echo "错误: " . $e->getMessage();
}

// 关闭连接
$conn = null;
?>