php 封装pdo

好的，下面是一个简单的 PHP PDO 封装类的示例：

class Database {
    private $host = "localhost";
    private $user = "username";
    private $password = "password";
    private $database = "database";
    private $charset = "utf8mb4";

    private $pdo;

    public function __construct() {
        $dsn = "mysql:host={$this->host};dbname={$this->database};charset={$this->charset}";
        $options = [
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
            PDO::ATTR_EMULATE_PREPARES => false,
        ];
        $this->pdo = new PDO($dsn, $this->user, $this->password, $options);
    }

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

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

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

    public function insert($table, $data) {
        $keys = array_keys($data);
        $values = array_values($data);
        $placeholders = implode(',', array_fill(0, count($values), '?'));
        $sql = "INSERT INTO $table (" . implode(',', $keys) . ") VALUES ($placeholders)";
        $this->query($sql, $values);
        return $this->pdo->lastInsertId();
    }

    public function update($table, $data, $where) {
        $set = [];
        $values = [];
        foreach ($data as $key => $value) {
            $set[] = "$key = ?";
            $values[] = $value;
        }
        $sql = "UPDATE $table SET " . implode(',', $set) . " WHERE $where";
        return $this->query($sql, $values)->rowCount();
    }

    public function delete($table, $where) {
        $sql = "DELETE FROM $table WHERE $where";
        return $this->query($sql)->rowCount();
    }
}

这个类封装了 PDO，包含了常用的查询操作，如 query、fetchAll、fetch，以及增删改操作，如 insert、update、delete。你可以根据自己的需要进行扩展。使用时，只需要实例化这个类，并调用相应的方法即可。例如：

$db = new Database();
$rows = $db->fetchAll("SELECT * FROM table WHERE id = ?", [1]);

这个示例会查询一个 ID 为 1 的记录，并返回一个数组。你可以根据需求进行修改。