php获取mysql错误

<?php
$host = 'localhost';
$user = 'username';
$password = 'password';
$dbname = 'database_name';

// 创建连接
$conn = new mysqli($host, $user, $password, $dbname);

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

// 执行查询
$sql = "SELECT id, name FROM users";
$result = $conn->query($sql);

if (!$result) {
    echo "查询错误: " . $conn->error;
}

// 关闭连接
$conn->close();
?>

<?php
$host = 'localhost';
$dbname = 'database_name';
$user = 'username';
$password = 'password';

try {
    $pdo = new PDO("mysql:host=$host;dbname=$dbname", $user, $password);
    $pdo->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    $sql = "SELECT id, name FROM users";
    $stmt = $pdo->query($sql);

    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        echo "ID: " . $row['id'] . " - Name: " . $row['name'] . "<br>";
    }
} catch (PDOException $e) {
    echo "数据库连接失败: " . $e->getMessage();
}
?>