example-auto-version/api/app/common/util/OrderHelper.php

<?php

namespace app\common\util;

use think\db\exception\DataNotFoundException;
use think\db\exception\DbException;
use think\db\exception\ModelNotFoundException;
use think\facade\Db;

class OrderHelper
{
    /**
     * 生成订单号
     * @param $user_id
     * @return string|null
     * @throws DataNotFoundException
     * @throws DbException
     * @throws ModelNotFoundException
     */
    public static function createOrderNo($user_id): ?string
    {
        for ($i = 0; $i < 10000; $i++) {
            //订单号规则 年月日时分秒+4位随机数+用户ID
            $no = date('YmdHis') . rand(1000, 9999) . $user_id;
            $exist = (new Db)->name('order')->where(["order_no" => $no])->find();

            if (!$exist) {
                return $no;
            }
        }
        return null;
    }
}