php数据库如何封装通用类 php数据库操作类的设计与实现

class Database {
    private $pdo;
    private $stmt;

    // 构造函数，建立数据库连接
    public function __construct($host = 'localhost', $dbname = 'test', $username = 'root', $password = '') {
        $dsn = "mysql:host={$host};dbname={$dbname};charset=utf8mb4";
        try {
            $this->pdo = new PDO($dsn, $username, $password, [
                PDO::ATTR_ERRMODE          => PDO::ERRMODE_EXCEPTION,
                PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
                PDO::ATTR_EMULATE_PREPARES => false,
            ]);
        } catch (PDOException $e) {
            throw new Exception('数据库连接失败：' . $e->getMessage());
        }
    }

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

    // 获取单行结果
    public function fetch() {
        return $this->stmt->fetch();
    }

    // 获取所有结果
    public function fetchAll() {
        return $this->stmt->fetchAll();
    }

    // 获取影响行数
    public function rowCount() {
        return $this->stmt->rowCount();
    }

    // 插入数据
    public function insert($table, $data) {
        $fields = array_keys($data);
        $placeholders = ':' . implode(', :', $fields);
        $sql = "INSERT INTO {$table} (" . implode(', ', $fields) . ") VALUES ({$placeholders})";
        return $this->query($sql, $data);
    }

    // 更新数据
    public function update($table, $data, $where, $whereParams = []) {
        $setPart = '';
        foreach ($data as $field => $value) {
            $setPart .= "{$field} = :{$field}, ";
        }
        $setPart = rtrim($setPart, ', ');

        $sql = "UPDATE {$table} SET {$setPart} WHERE {$where}";
        $params = array_merge($data, $whereParams);
        return $this->query($sql, $params);
    }

    // 删除数据
    public function delete($table, $where, $params = []) {
        $sql = "DELETE FROM {$table} WHERE {$where}";
        return $this->query($sql, $params);
    }

    // 根据主键查找
    public function find($table, $id, $primaryKey = 'id') {
        $sql = "SELECT * FROM {$table} WHERE {$primaryKey} = :id";
        return $this->query($sql, ['id' => $id])->fetch();
    }

    // 查找所有
    public function findAll($table) {
        $sql = "SELECT * FROM {$table}";
        return $this->query($sql)->fetchAll();
    }

    // 获取最后插入的ID
    public function lastInsertId() {
        return $this->pdo->lastInsertId();
    }
}

$db = new Database('localhost', 'myapp', 'root', '123456');

// 查询单条数据
$user = $db->find('users', 1);
var_dump($user);

// 查询所有
$users = $db->findAll('users');
var_dump($users);

// 插入数据
$db->insert('users', [
    'name' => '张三',
    'email' => 'zhangsan@example.com',
    'created_at' => date('Y-m-d H:i:s')
]);
echo "新增ID：" . $db->lastInsertId();

// 更新数据
$db->update('users', 
    ['name' => '李四'], 
    'id = :id', 
    ['id' => 1]
);

// 删除数据
$db->delete('users', 'id = :id', ['id' => 1]);