SELECT
     Klient.client_last_name AS Nazwisko
    ,Klient.client_first_name AS [Imie]
    ,Kraj.country_name AS [Kraj (hotel)]
    ,Miasto.city_name AS [Miasto (hotel)]
    ,reservation_starting_date AS [Data rozpoczecia rezerwacji]
    ,reservation_final_date AS [Data zakończenia rezerwacji]
    ,CASE
        WHEN Rezerwacja.reservation_realized = 1 THEN 'Zrealizowana'
        ELSE 'NIE zrealizowana'
     END AS [Stan realizacji]
FROM
    reservations Rezerwacja
    JOIN clients Klient ON Rezerwacja.reservation_client_id = Klient.client_id
    JOIN rooms Pokoj ON Rezerwacja.reservation_room_id = Pokoj.room_id
    JOIN hotels Hotel ON Pokoj.room_hotel_id = Hotel.hotel_id
    JOIN countries Kraj ON Hotel.hotel_country_id = Kraj.country_id
    JOIN cities Miasto ON Hotel.hotel_city_id = Miasto.city_id
WHERE
    Klient.client_last_name = 'Banko'

DECLARE @ile_hoteli numeric =
    (
        SELECT
            COUNT(*)
        FROM    
            hotels
    )   
SELECT
     C.country_name AS Kraj
    ,CAST(COUNT(*)*100/@ile_hoteli AS NUMERIC(6,2)) AS [%]
FROM
    hotels H
    JOIN countries C ON H.hotel_country_id = C.country_id    
GROUP BY
    C.country_name
ORDER BY
    2 DESC   

DECLARE @dataSprawdzenia date = '2016-10-10'
DECLARE @ilePokoi int =
    (
        SELECT
            COUNT(*)
        FROM
            rooms
    )
DECLARE @ilePokoiZajetych int =
    (    
        SELECT
            COUNT(*)    
        FROM    
            reservations R    
        WHERE
            @dataSprawdzenia BETWEEN R.reservation_starting_date AND R.reservation_final_date
    )    
DECLARE @oblozenie REAL = 100*@ilePokoiZajetych/@ilePokoi;
SELECT
     'Wszystkich pokoi: '+CAST(@ilePokoi AS NVARCHAR) AS Pokoi
    ,'Zajętych pokoi: '+CAST(@ilePokoiZajetych AS NVARCHAR) AS Zajętych
    ,'Obłożenie pokoi w dn. 2016-10-10 wynosi: '
        +CAST(CAST(ROUND((100*CAST(@ilePokoiZajetych AS NUMERIC)/CAST(@ilePokoi AS NUMERIC)),2) AS NUMERIC(6,2)) AS NVARCHAR)
        +'%' AS Obłożenie

SELECT TOP 1
     CO.country_name AS Kraj
    ,CI.city_name AS Miasto
    ,H.hotel_id AS [Nazwa hotelu]
    ,COUNT(*) AS [Ilość złożonych rezerwacji]
FROM
    reservations RE
    JOIN rooms RO ON RE.reservation_room_id = RO.room_id
    JOIN hotels H ON RO.room_hotel_id = H.hotel_id
    JOIN countries CO ON H.hotel_country_id = CO.country_id
    JOIN cities CI ON H.hotel_city_id = CI.city_id
WHERE
    RE.reservation_realized = 1
GROUP BY
    CO.country_name , CI.city_name , H.hotel_id        
ORDER BY
    COUNT(*) DESC

SELECT TOP 1
     CO.country_name AS Kraj
    ,CI.city_name AS Miasto
    ,H.hotel_id AS [Nazwa hotelu]
    ,COUNT(*) AS [Ilość złożonych rezerwacji]
FROM
    reservations RE
    JOIN rooms RO ON RE.reservation_room_id = RO.room_id
    JOIN hotels H ON RO.room_hotel_id = H.hotel_id
    JOIN countries CO ON H.hotel_country_id = CO.country_id
    JOIN cities CI ON H.hotel_city_id = CI.city_id
GROUP BY
    H.hotel_id , CO.country_name , CI.city_name
ORDER BY
    COUNT(*) DESC

DECLARE @max_parking_places int = (
SELECT TOP 1
    COUNT(P.parking_hotel_id)
FROM
    parking P    
GROUP BY
    P.parking_hotel_id
ORDER BY
    1 DESC
);
SELECT
     H.hotel_name AS [Nazwa hotelu]
    ,COUNT(P.parking_hotel_id) AS [Ilość miejsc parkingowych]
FROM
    parking P    
    JOIN hotels H ON P.parking_hotel_id = H.hotel_id
GROUP BY
    P.parking_hotel_id, H.hotel_name
HAVING    
    COUNT(P.parking_hotel_id) = @max_parking_places   

DECLARE @ilosc_dni int =
    (
        SELECT TOP 1
            DATEDIFF(day,reservation_starting_date,reservation_final_date) AS Dni
        FROM
            reservations R    
        ORDER BY
            1 DESC            
    )    
    
SELECT
     *
FROM
    reservations R        
WHERE
    DATEDIFF(day,reservation_starting_date,reservation_final_date) = @ilosc_dni