DatabaseApplication/app/Models/Client.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Factories\HasFactory;
use Illuminate\Database\Eloquent\Model;

class Client extends Model
{
    use HasFactory;

    protected $fillable = ['firstname', 'lastname', 'phone'];

    public function orders() {
        return $this->hasMany('App\Models\Order');
    }
    
}