This is a very old question, but it comes up prominently in searches.

In Laravel 12.x (current in 2025) you have DB::selectOne() for the first row, and DB::scalar() for the first value:

$weekOfYear = DB::scalar("SELECT DATE_PART('week', CURRENT_DATE) woy");

https://laravel.com/docs/11.x/database#selecting-scalar-values