erp/app/Listeners/SendDatabaseNotification.php

<?php

namespace App\Listeners;

use Illuminate\Contracts\Queue\ShouldQueue;
use Illuminate\Queue\InteractsWithQueue;
use App\Events\BusinessOrdersUpdate;

class SendDatabaseNotification implements ShouldQueue
{
    use InteractsWithQueue;

    /**
     * Create the event listener.
     *
     * @return void
     */
    public function __construct()
    {
        //
    }

    /**
     * Handle the event.
     *
     * @param BusinessOrdersUpdate $event
     * @return void
     */
    public function handle(BusinessOrdersUpdate $event)
    {
        if (5 >= $event->goodsSku->stock) {
            // 发送通知给管理员
        }
    }
}