default database not taking in laravel code example

Example 1: DB::transaction

use Illuminate\Support\Facades\DB;

DB::transaction(function () {
    DB::update('update users set votes = 1');

    DB::delete('delete from posts');
});

Example 2: TRANSACTON LARAVEL QUERY BUILDER

DB::beginTransaction();

try {
    DB::insert(...);    
    DB::commit();
} catch (\Throwable $e) {
    DB::rollback();
    throw $e;
}