Question

I have the next question:
What is the most commonly booked room type for each hotel in New-York?

Tables:

 1. Hotel - city, hotelNo[primarykey]
 2. Room - roomNo[primarykey], type, hotelNo[foreignkey]
 3. Booking - roomNo[foreignkey], hotelNo[foreignkey]

So, let’s say I have 3 hotels in the city and I need to get the table with columns:——–

NumberOfBookings, MostBookedType, HotelName

Any suggestions? Thanks in advance!

Here’s my code:

SELECT type, r.hotelNo, r.roomNo
FROM room r
INNER JOIN booking b ON r.roomNo=b.roomNo
WHERE r.hotelNo = ANY
(
   SELECT hotelNo
   FROM hotel
   WHERE city = "New York"
)

It shows type of rooms, No of hotel, and roomNo of ever made bookings in hotels of New York.

I need to find out how to create a table showing type (that was mostly booked), numberOfBookings (of the most booked type), hotelNo (of the room type)

Answer 1

select
      hotel.city HotelName,
      room.type BookedType,
      count(*) NumberOfBookings
   from
      Booking B
         join Hotel
            on B.HotelNo = Hotel.HotelNo
         join Room
            on B.HotelNo = Room.HotelNo
           AND B.RoomNo = room.RoomNo
   group by
      B.HotelNo,
      room.Type
   order by
      count(*) desc

Now, this routine could pull Queen Bed from Hotel A first, with Double Bed from Hotel X second with Double Bed from Hotel A third, and King from Hotel A forth… As it appears you specifically wanted per hotel AND type of room…

I would ensure you have an index on your booking table based on (HotelNo, RoomNo) to help optimizing the group by…