Question

I have been trying to solve this for a while now, any help would be greatly appreciated.

I have tables:

distributor(distributor_name, distributor_id)
distributed(price, movie_id, distributor_id)
movie(title, movie_id)

Each distributor has multiple records for movies at different prices.

I am trying to select the minimum price for a particular movie and from what distributor

so far I have tried:

select min(Price), Distributor from
(select m.distributor_name as Distributor, d.price from 
distributors m, distributed d, movies mo
where
mo.title = 'Movie Name' and mo.movie_id = d.movie_id and d.distributor_id = m.distributor_id)
group by Distributor;

Which returns the minimum price for each distributor.

If I run:

select min(Price)
(select m.distributor_name as Distributor, d.price from 
distributors m, distributed d, movies mo
where
mo.title = 'Movie Name' and mo.movie_id = d.movie_id and d.distributor_id = m.distributor_id);

It gives just the lowest price of that particular movie.

How can I get the name of the distributor for the lowest price?

Answer 1

Depending on your version of Oracle, you can use row_number():

select price, distributor
from
(
  select d.price, 
    m.distributor_name as Distributor,
    row_number() over(order by d.price) rn
  from distributors m
  inner join distributed d
    on d.distributor_id = m.distributor_id
  inner join movies mo 
    on mo.movie_id = d.movie_id 
  where mo.title = 'Movie Name' 
) src
where rn = 1;

See SQL Fiddle with Demo

If you wanted to expand on this and get the lowest price for any movie, then you could partition the data by movie title:

select price, distributor
from
(
  select d.price, 
    m.distributor_name as Distributor,
    row_number() over(partition by mo.title order by d.price) rn
  from distributors m
  inner join distributed d
    on d.distributor_id = m.distributor_id
  inner join movies mo 
    on mo.movie_id = d.movie_id 
) src
where rn = 1;