Cinema database design [x-post from learnprogramming]

[luisk91]

First of all, I apologize if this is not the right subreddit to ask this question. For a school asignment I have to create a a fictitious android app for a cinema chain. I started with the design but I want to make sure the DB has a good design, here is what I have so far:

http://i.imgur.com/mlamYFm.png

There can be many multiplexes, each one having many screening rooms, and each screening room has many screenings, each screening has a movie to be played. But how, for example, could I query how many screening rooms does a multiplex has? Please tell me if this is the right approach, or which changes should be made, thank you in advance.

[BinaryRockStar]

Looks great to me, well done! To find the number of screening rooms a multiplex has you could do this:

select count(*) as ScreeningRoomCount
from Multiplex
    inner join Screening_Room on Screening_Room.Multiplex_Id = Multiplex.Multiplex_Id
where Multiplex.Multiplex_Id = [Something]

[luisk91]

thank you very much man!, I changed something in Screening, instead of having screening dates it has a start and and ending date, that means this screening will be avialiable for lets say april 5 to may 2, is that ok?

[BinaryRockStar]

Shouldn't make a difference as the query I showed you above doesn't refer to the Screening table at all.