liwo/database/seeds/SprintSeeder.php

<?php

use App\Sprint;
use Illuminate\Database\Seeder;

class SprintSeeder extends Seeder
{
    public function run()
    {
        $sprints = [];
        for ($business_id=1; $business_id <= 2000; $business_id++) {
            for ($i=0; $i < rand(0, 10); $i++) {
                $sprints[] = factory(Sprint::class)->raw([
                    'business_id' => $business_id,
                    'project_id' => rand(1, 4027),
                ]);
            }
        }
        DB::table('sprints')->insertOrIgnore($sprints);
    }
}