Create query in Librries

How to use database library in libraries?

I try this:

PHP Code:

<?php


namespace App\Libraries;

class Test   {
        
   
    public function test()
        {
           
        $db = \Config\Database::connect();
        $query = $db->query('SELECT * FROM test');
        $results = $query->getResult();
        print_r($results);
        
        }
}