In PHP, what are the advantages and disadvantages of using static methods like DB::first for database queries, and how can they impact the accuracy of results?

Using static methods like DB::first for database queries can provide a convenient way to access database functionality without the need to instantiate a new database connection object each time. However, it can lead to issues with testability and maintainability as static methods are tightly coupled and harder to mock in unit tests. To improve accuracy and flexibility, consider using dependency injection to pass the database connection object to the class or method that needs it.

class DB {
    public static function first($query) {
        $db = new DatabaseConnection();
        return $db->query($query)->fetch();
    }
}

class UserRepository {
    private $db;

    public function __construct(DatabaseConnection $db) {
        $this->db = $db;
    }

    public function getUserById($id) {
        return $this->db->query("SELECT * FROM users WHERE id = $id")->fetch();
    }
}

// Example of using UserRepository with dependency injection
$db = new DatabaseConnection();
$userRepository = new UserRepository($db);
$user = $userRepository->getUserById(1);