I was going to ask about it earlier as I've noticed the problem with the Posts table declaration (Performance concerns):

// in database/migrations/{date_time}_create_posts_table.php
Schema::create('posts', function (Blueprint $table) {
            $table->id();
            $table->foreignId('user_id');
            $table->foreignId('category_id');

That statement does NOT generate the Foreign Keys - just the fields with the names provided. This can be confirmed in table declaration - no extra Indexes and no ForeignKey declarations -> here are the screenshots from MySQL Workbench

Indexes - just Primary and Slug
Foreign Keys - nothing at all
Cost of query (6.75) posts by the author -> requires a Full Table Scan

To create a proper ForeignKeys statements and the DB structure it looks like that constrained method should be used every time (for a proper ForeignKey declaration)

// in database/migrations/{date_time}_create_posts_table.php
Schema::create('posts', function (Blueprint $table) {
            $table->id();
            $table->foreignId('user_id')->constrained();
            $table->foreignId('category_id')->constrained();

To make it work (when seeding DB) the migration file for {date_time}_create_categories_table.php must be executed FIRST!!! So, if you've followed that tutorial, you need to adjust the {date_timestamp} for ...create_categories... file to one day or hour earlier (before ...create_posts...)

Cascade or not is a separate matter.

Here are results from Workbench after those changes applied and migrate:fresh --seed

Indexes
Foreign Keys
Cost of query this time just (0.85) thanks to additional key

BTW

Here is my code to use more random data seeder. It generates from 3 to 8 posts per each user and each post belongs to a random category. In total it generates 50+ posts.

class DatabaseSeeder extends Seeder
{
    const CATEGORIES_AMOUNT = 10;
    const USERS_AMOUNT = 10;

    public function run(): void
    {
        $users = User::factory(self::USERS_AMOUNT)->create();
        Category::factory(self::CATEGORIES_AMOUNT)->create();
        foreach ($users as $user) {
            Post::factory(rand(3, 8))->create(
                [
                    'user_id' => $user->id, 
                    'category_id' => fn() => rand(1, self::CATEGORIES_AMOUNT)
                ]
            );
        }
    }
}

Table Consistency and Foreign Key Constraints

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