SQLPad
Instruction
- Write a query to return the titles of the films with
>= 10actors.
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.