<?php

try {

    $pdo = new PDO(
        'mysql:dbname=testdb;host=localhost;charset=utf8',
        'root',
        '',
        array(
            PDO::ATTR_EMULATE_PREPARES => false,
            PDO::ATTR_ERRMODE => PDO::ERRMODE_EXCEPTION,
            PDO::ATTR_DEFAULT_FETCH_MODE => PDO::FETCH_ASSOC,
        )
    );
    $offset = isset($_GET['offset']) ? max(0, (int)$_GET['offset']) : 0;
    $sql = implode(' ', array(
        'SELECT id, point',
        'FROM point',
        'ORDER BY point DESC',
        'LIMIT 5',
        'OFFSET ' . $offset
    ));
    $data = array();
    foreach ($pdo->query($sql) as $i => $row) {
        $data[] = array(
            'rank'  => $offset + $i + 1,
            'id'    => $row['id'],
            'point' => $row['point'],
        );
    }
    header('Content-Type: application/json; charset=utf-8');
    echo json_encode(compact('data'));

} catch (Exception $e) {

    $error = $e->getMessage();
    header('Content-Type: application/json; charset=utf-8', true, 500);
    echo json_encode(compact('error'));

}