blog_tp6/app/model/NovelData.php

<?php
namespace app\model;

class NovelData extends \think\Model
{
    protected $pk = 'id';

    public static function getNextPrev($id, $nid = null)
    {
        $whereP = [];
        $whereN = [];

        // $whereP[] = ['status', '=', 1];
        // $whereN[] = ['status', '=', 1];
        
        if ($nid) {
            $whereP[] = ['n_id', '=', $nid];
            $whereN[] = ['n_id', '=', $nid];
        }

        $whereP[] = ['id', "<", $id];
        $whereN[] = ['id', ">", $id];

        $data_P = self::where($whereP)->order("id asc")->limit(1)->find();
        $data_N = self::where($whereN)->order("id asc")->limit(1)->find();

        return ['prev' => $data_P, 'next' => $data_N];
    }

}