Laravel Seed update a column from column on another table

I have two tables that I am using.

for example I am going to use posts.

The first is the posts table

id|name |author|author_id|country
1 |test |Devin |1        |South Africa
2 |test2|James |2        |Whales
3 |test3|Devin |1        |South Africa

Then I have the authors table

id|name
1 |Devin
2 |James

I want to add countries to the Authors table. So I made a migration to get my table to look like this

id|name  |country
1 |Devin |NULL
2 |James |NULL

Now what I am trying to achieve is to write a database seeder that will seed the countries into the authors table based on the posts table.

I want to grab the posts country for that author_id and then insert the country into the author table so that it will look like this

id|name  |country
1 |Devin |South Africa
2 |James |Whales

My question is, is it possible to do this using a seeder? Or is there a better way to do this without having to do it manually for every author.

I thought to do something like this

<?php

use Illuminate\Database\Seeder;

class AlterOperatorsData extends Seeder
{
    /**
     * Run the database seeds.
     *
     * @return void
     */
    public function run()
    {
        $authors = Author::all();

        foreach ($authors as $author) {
            $country = App\Post::where('author_id', $author->id);
            DB::table('authors')->update([
                'country' => $country->country
            ]);
        }
    }
}

But that looks like it would do some heavy lifting, can anyone suggest a better method, or even take a look at the current method to see if it can be improved?

via Chebli Mohamed