how to set primary key in laravel migration code example

Example 1: laravel rollback last migration

php artisan migrate:rollback --step=1

Example 2: laravel migration foreign key 5.6

Schema::table('posts', function (Blueprint $table) {
    $table->unsignedInteger('user_id');

    $table->foreign('user_id')->references('id')->on('users');
});

Example 3: laravel create migration

php artisan make:migration add_votes_to_users_table --table=users

php artisan make:migration create_users_table --create=users

Example 4: php artisan see last migration

php artisan migrate:status