RailwayTwo/app/Models/Order.php

<?php

namespace App\Models;

use Carbon\Carbon;

class Order extends BaseModel
{
    public static function createOrderNumber()
    {
        $times = 10;
        $str = substr(Carbon::now()->format('Ymdhis'), 2);
        do {
            $str = $str . mt_rand(10000, 99999);
            $res = self::where('order_number', $str)->first();
            if(!$res) break;
            $times = $times - 1;
        } while($times);

        return $str;
    }

    public function user()
    {
        return $this->belongsTo('App\Models\User', 'user_id');
    }
}