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Posted by Egor, July 15, 2022, 1:50 a.m.

44, less not-in-demand films

Hi, All

 

Just make sure once again, whether you apply any where conditions on top of left joined tables/ctes, and maybe it is better to keep them as join conditions and then use count for specific column to not count rows with null values.

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Hi Egor,

Your code looks good, you are missing the films that are not in the inventory table, we assume that if a movie is not in stock, it's not in demand.

Thanks,

Leon

 

 

Hi, Leon

Thank you for your answer.  I am missing more than 200 films, but there are only 42 films that exist in film and don't exist in inventory. And they were included in my query. Sorry, if I don't see something evident. 

select count(film_id)
from film f
where not exists(
      select 1
      from inventory i
      where i.film_id = f.film_id
);

count
42

Egor, July 17, 2022, 8:46 p.m.
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Leon (949)

July 17, 2022, 3:14 p.m.