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lab_sql_advancedqueries_imb_solution.sql
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lab_sql_advancedqueries_imb_solution.sql
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############################################
################# UNIT | 3 #################
############################################
####### LAB | SQL | Advanced Queries #######
############################################
USE sakila;
# 01. For each film, list actor that has acted in more films
-- Which tables? film_actor
-- Which keys? actor_id, film_id
WITH actor_film_count AS -- CTE to count the number of films per actor
(SELECT actor_id, COUNT(film_id) AS acted
FROM film_actor
GROUP BY actor_id)
SELECT F.film_id, F.actor_id, A.acted
FROM film_actor AS F
JOIN actor_film_count AS A
ON F.actor_id = A.actor_id -- Join film_actor with CTE
WHERE A.acted = -- Filter: actors with most films for each film_id
(SELECT MAX(B.acted) -- max acted count for each film_id
FROM film_actor AS FA
JOIN actor_film_count AS B
ON FA.actor_id = B.actor_id -- Join film_actor with CTE
WHERE F.film_id = FA.film_id)
ORDER BY F.film_id ASC;
-- I got lost in this SQL, and I used this as a reference (JesusC answer)
WITH actor_film AS
(SELECT actor_id, COUNT(film_id) AS acted
FROM film_actor
GROUP BY actor_id),
ranking AS
(SELECT F.film_id, F.actor_id, A.acted, RANK() OVER (PARTITION BY film_id ORDER BY acted DESC) AS rank_actors
FROM film_actor AS F
JOIN actor_film AS A
USING (actor_id))
SELECT film_id, actor_id
FROM ranking
WHERE rank_actors = 1;