24. Films with more than 10 actors

medium

Instruction

  • Write a query to return the titles of the films with >= 10 actors.

Table 1: film

       col_name       |  col_type
----------------------+--------------------------
 film_id              | integer
 title                | text
 description          | text
 release_year         | integer
 language_id          | smallint
 original_language_id | smallint
 rental_duration      | smallint
 rental_rate          | numeric
 length               | smallint
 replacement_cost     | numeric
 rating               | text

Table 2: film_actor

Films and their casts

  col_name   | col_type
-------------+--------------------------
 actor_id    | smallint
 film_id     | smallint

Sample results

         title
------------------------
 ACADEMY DINOSAUR
 ARABIA DOGMA

Expected results

Solution postgres

WITH film_casts_cnt AS (
	SELECT 
	    film_id,
	    COUNT(*) AS actors_cnt
	FROM film_actor
	GROUP BY film_id
	HAVING COUNT(*)>=10
)

SELECT title
FROM film
WHERE film_id IN (
    SELECT film_id
    FROM film_casts_cnt
)
    

Explanation

This query is selecting the titles of all films that have 10 or more actors in their cast.

The first part of the query creates a temporary table called "film_casts_cnt" which contains the count of actors in each film. It does this by grouping the "film_actor" table by film_id and counting the number of rows in each group. It then filters this table to only include films with 10 or more actors.

The second part of the query selects the titles of all films where the film_id is in the "film_casts_cnt" table. This effectively joins the two tables on the film_id column and returns the title for each matching row.



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