使用PHP PDO的数据库抽象类设计

<?php
abstract class Database
{
    protected $pdo;

    public function __construct($host, $username, $password, $database)
    {
        $dsn = "mysql:host=$host;dbname=$database;charset=utf8mb4";
        $options = [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES => false,
        ];

        try {
            $this->pdo = new PDO($dsn, $username, $password, $options);
        } catch (PDOException $e) {
            die("Database connection failed: " . $e->getMessage());
        }
    }

    public function query($sql, $params = [])
    {
        $stmt = $this->pdo->prepare($sql);
        $stmt->execute($params);
        return $stmt;
    }

    // 其他数据库操作方法，如insert、update、delete等

    abstract public function getTableName();
}

class UserDatabase extends Database
{
    public function getTableName()
    {
        return 'users';
    }

    public function getUserById($id)
    {
        $sql = "SELECT * FROM " . $this->getTableName() . " WHERE id = :id";
        $stmt = $this->query($sql, [':id' => $id]);
        return $stmt->fetch();
    }

    // 其他用户相关的数据库操作方法
}

// 使用示例
$userDb = new UserDatabase('localhost', 'username', 'password', 'database');
$user = $userDb->getUserById(1);
print_r($user);