SQL Multiple Inner Joins on the same field

Question

I am currently working as a programmer in a small startup aiming on providing pay-per-view content online and I have been assigned to develop the metadata database for the movie catalogue

I have two main tables, movie and people , where *movie_ID* and *people_ID* are the primary keys respectively for each table. Both tables have a many-to-many relationship.

To represent different relations I am currently using link tables, for example, actor_movie would store the *movie_ID* and corresponding *people_ID* for each of the actors in the movie, while the director_movie table would store the *movie_ID* and the director(s) *people_ID*. Same goes for writer, composers and producers.

Now, my problem is that I need to craft out a query that returns all the actors, directors, producers, writers, composers, etc. etc. in one single table to be passed on the frontend Web UI as a list of all the persons involved in the movie.

I'm currently stumped as to how to create a multiple SELECT query that would JOIN all the link tables together based on the *movie_ID* and *people_ID* and then return the details of each of the person in the people table as well.

And example of what I have written so far is:

SELECT
movie.titleMovie,
people.namePeople,
FROM 
movie movie

INNER JOIN actorlinkmovie acm ON acm.idMovie = movie.idMovie
INNER JOIN people people ON people.idPeople = acm.idPeople

What I would like to have happen is:

SELECT
movie.idMovie,
movie.titleMovie,
movie.descMovie,
movie.dateMovie,
movie.runtimeMovie,
movie.langMovie,
movie.ratingMovie,
people.namePeople
FROM 
htv_movie movie

INNER JOIN htv_actorlinkmovie acm ON acm.idMovie = movie.idMovie
INNER JOIN htv_directorlinkmovie dcm ON dcm.idMovie = movie.idMovie
INNER JOIN htv_producerlinkmovie pcm ON pcm.idMovie = movie.idMovie
INNER JOIN htv_people people WHERE people.idPeople = dcm.idPeople AND people.idPeople = acm.idPeople AND people.idPeople = pcm.idPeople

And it should return the all the related people from a single movie.

Would like to get some input about the whole design since I'm a pretty new at designing a whole database (first time actually) and whether would this design be suitable if I need to scale up to about 5000 movies (the current company aim). This database will pretty much serve as the website's backend as well.

Thanks.

UPDATE: Temporarily worked out a dirty solution using PHP variables and a template SQL query. Looks like doing multiple inner joins wasn't that required after all. Thanks for the suggestions though.

Answer 1

You can achieve your goal like this:

SELECT MovieName, dbo.GetDirector(MovieID), dbo.GetActors(MovieID), dbo.GetWriter(MovieID) FROM Movie

where

• dbo.GetDirector(MovieID) is a function that will return directors in the movie.
• dbo.GetActors(MovieID) is a function that will return actors in the movie.
• dbo.GetWriter(MovieID) is a function that will return writers in the movie.

If there are some other tables then you can make functions for those tables as well.

Hope this helps.