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+
+## Ejercicios de consultas a tablas
+
+```sql
+select count (title) from film;
+
+select count (*) from film;
+
+select avg(rental_rate) from film;
+
+select title, 
+	rental_rate, 
+	replacement_cost, 
+	round(replacement_cost/rental_rate, 2) as percentage 
+from public.film;
+
+select title,
+	ceil(replacement_cost/rental_rate) as rents_to_profit
+from public.film;
+
+select *
+from film
+where 2 < rental_rate and rental_rate > 3;
+
+select title, rental_rate
+from public.film
+where rental_rate between 2 and 3;
+
+select title, 
+	rental_rate, 
+	release_year
+from public.film
+where title like 'A%s'
+	and rental_rate between 2 and 3
+	and release_year = 2006
+	and title is not null;
+
+select first_name,
+	last_name
+from public.actor
+where first_name like 'A%';
+
+select title,
+	rental_rate
+from public.film
+where rental_rate > 10;
+
+select title,
+	rental_rate
+from public.film
+where rental_rate between 5 and 10;
+
+select title,
+	rental_rate,
+	f.length
+from public.film as f
+where rental_rate < 5
+	and length < 100;
+	
+select title, 
+	rental_rate
+from public.film
+where title like 'Gi%';
+
+select title, 
+	rating,
+	f.length
+from public.film as f
+where title = 'Ali Forever';
+
+select title,
+	rental_rate
+from public.film
+where rental_rate is null;
+
+select title,
+	f.length
+from public.film as f
+order by length
+limit 5;
+
+select rating,
+	count(distinct title) as películas,
+	round(avg(rental_rate),2) as precio_medio,
+	min(rental_rate) as precio_más_bajo,
+	max(rental_rate) as precio_más_alto,
+	round(avg(f.length),2) as duración,
+	min(release_year) as más_antigua,
+	max(release_year) as más_nueva
+from public.film as f
+group by rating
+having avg(f.length) > 110;
+
+select rating,
+	count(distinct title) as películas,
+	round(avg(rental_rate),2) as precio_medio,
+	round(avg(f.length),2) as duración
+from public.film as f
+group by rating
+having count(distinct title) > 200
+	and avg(rental_rate) > 3
+	and avg(f.length) > 115;
+	
+select customer.first_name,
+	customer.last_name,
+	address.address
+from public.customer customer
+	inner join public.address address 
+	on customer.address_id = address.address_id
+limit 10;
+
+-- ficha de cliente: nombre, país, ciudad y dirección
+select customer.first_name,
+	customer.last_name,
+	country.country,
+	city.city,
+	address.address
+from public.customer customer
+	left join public.address address 
+		on customer.address_id = address.address_id
+	left join public.city city
+		on address.city_id = city.city_id
+	left join public.country country
+		on city.country_id = country.country_id
+limit 10;
+
+-- ¿cuántos actores tiene cada película?
+select f.title,
+	count(distinct a.actor_id) as actores
+from public.actor a
+	left join public.film_actor fa
+		on a.actor_id = fa.actor_id
+	left join public.film f
+		on fa.film_id  = f.film_id
+group by f.title
+order by count(distinct a.actor_id) desc;
+
+-- ¿cuáles son las películas que tienen más de dos actores?
+select f.title,
+	count(distinct a.actor_id) as actores
+from public.actor a
+	left join public.film_actor fa
+		on a.actor_id = fa.actor_id
+	left join public.film f
+		on fa.film_id  = f.film_id
+group by f.title
+having count(distinct a.actor_id) > 2
+order by count(distinct a.actor_id) desc;
+
+-- ¿cuál es la película que tiene más actores?
+select f.title,
+	count(distinct a.actor_id) as actores
+from public.actor a
+	left join public.film_actor fa
+		on a.actor_id = fa.actor_id
+	left join public.film f
+		on fa.film_id  = f.film_id
+group by f.title
+order by count(distinct a.actor_id) desc
+limit 1;
+```
+
+## Ejercicios de creación de tablas y de inserción de datos
+
+```sql
+-- crear tabla
+create table if not exists public.reviews(
+	film_id integer not null,
+	customer_id integer not null,
+	review_date date not null,
+	review_description character varying(50) not null,
+	constraint film_customer_pkey
+		primary key (film_id, customer_id) -- una sola primary key compuesta por dos campos
+	);
+```
+
+```sql
+-- insertar datos en nuestra tabla reviews
+insert into public.reviews (film_id, customer_id, review_date, review_description)
+	values (1234,5678,'01-01-2024','ok');
+
+-- sobreescribir un campo
+update public.reviews
+set review_description = 'good'
+where film_id = 1234
+
+-- borrar un registro
+delete
+from public.reviews
+where film_id = 1234
+
+-- borrar tabla entera
+drop table public.reviews
+
+--función ALTER 
+
+Añade una nueva columna a la tabla de reviews que te parezca interesante. Por ejemplo, el número de
+estrellas que le darías a una película. Puedes llamarle “review_stars” y con datatype int2
+
+ALTER TABLE reviews_ng 
+ADD COLUMN review_stars INT2
+
+
+Renombra una de las columnas de la tabla de reviews. Por ejemplo, renombra la columna
+“review_description” a “review_opinion”
+
+ALTER TABLE reviews_ng 
+RENAME COLUMN review_description
+to review_opinion ;
+
+
+Cambia el tipo de dato de la columna de “review_stars” a varchar. Ahora es
+in int2.
+
+ALTER TABLE reviews_ng 
+ALTER COLUMN review_stars TYPE VARCHAR;
+
+
+Borra la columna de “review_stars”
+
+Eliminar 
+ALTER TABLE reviews_ng 
+DROP COLUMN review_stars;
+
+Views: para los que toman decisiones
+
+select * from actor_info ai
+
+Crear una nueva vista 
+CREATE VIEW my_view_of_actor AS
+SELECT actor_id, first_name, last_name, last_update
+FROM public.actor
+where first_name is not null;
+
+Crear mi propia view 
+CREATE VIEW my_view_martamr AS
+SELECT actor_id, first_name, last_name, last_update
+FROM public.actor
+where first_name is not null;
+
+select * from my_view_martamr
+
+ejemplo condicional 
+
+select length,
+case when length > 100 then 'PELICULA_LARGA'
+when length >50 and Length < 99 then 'PELICULA_MEDIA'
+else 'PELICULA_CORTA' END
+from film
+ 
+
+Concatenar
+select first_name, last_name, first_name || ' ' || last_name as nombre_completo, concat(first_name, ' ', last_name)
+from actor a
+
+Para sacar los clientes que más consumen: 
+
+select concat(first_name, ' ', last_name) as nombre_completo, sum(p.amount)
+from payment p
+inner join customer c on c.customer_id = p.customer_id
+group by 1
+order by 2 desc;
+ 
+Fechas
+
+SELECT (return_date::date - rental_date::date) AS difference_in_days,
+return_date::date, rental_date::date, rental_id::varchar
+from rental r ; 
+
+Query top 5 clientes 
+
+CREATE or replace view top5 AS
+select concat(first_name, ' ', last_name) as nombre_completo, sum(p.amount)
+from payment p
+inner join customer c on c.customer_id = p.customer_id
+group by 1
+order by 2 desc
+limit 5;
+ 
+CREATE or replace view down5 AS
+select concat(first_name, ' ', last_name) as nombre_completo, sum(p.amount)
+from payment p
+inner join customer c on c.customer_id = p.customer_id
+group by 1
+order by 2 asc
+limit 5;
+
+Para unir 2 views:
+
+select * from down5
+union all 
+select * from top5 
+
+
+Hacer KPI de la vista de top 5: 
+
+create view kpis as
+select avg(down5.sum) , 'down5' as tipo from down5
+union all
+select avg(top5.sum), 'top5' as tipo from top5 ;
+ 
+select * from kpis ;
+  
+
+Subconsultascon WHERE: 
+
+SELECT actor_id, first_name, last_name, last_update
+FROM public.actor
+where first_name in (select first_name from
+public.actor where last_name ilike 'C%')
+
+Ejemplo join vs subconsulta 
+
+select sum(p.amount) from payment p
+left join customer c on c.customer_id =p.customer_id
+where c.first_name  ilike 'C%'
+ 
+select sum(p.amount) from payment p
+where customer_id in (
+	select customer_id from customer c where first_name  ilike 'C%'
+)
+
+
+Subconsultas con with 
+
+with my_sub_query as
+(SELECT title, rental_rate, replacement_cost, round(replacement_cost / rental_rate, 2) as new_column
+FROM public.film),
+new_1 as
+(SELECT title, rental_rate, replacement_cost, round(replacement_cost / rental_rate, 2) as new_column
+FROM public.film)
+select * from new_1 where title = 'Ali Forever'
+ 
+
+Obtén haciendo una subconsulta en la cláusula WITH
+- La suma de los amount que de los clientes que han pagado más
+de 190€
+
+Sub: 
+
+with my_sub_query as 
+(select customer_id, sum(amount) total
+from paymnets 
+group by 1
+
+consulta: 
+select * from sub 
+where total> 190
+
+
+como quedaría:
+
+with sub as
+(select customer_id, sum(amount) as total
+from payment p 
+group by customer_id
+)
+select * from sub where total >190; 
+
+
+empleado del mes: 
+
+with top_employer as
+	(
+	select p.staff_id as staff_id,
+		sum(p.amount) as amount,
+		count(distinct customer_id) as clientes
+	from payment p
+	group by p.staff_id
+	order by sum(p.amount) desc
+	limit 1
+	),
+	sub_address as (
+	select a.address as address,
+		s.staff_id as staff_id,
+		(s.first_name || ' ' || s.last_name) as full_name
+	from staff s
+		left join address a
+		on a.address_id = s.address_id
+	),
+	rental_duration as (
+	select r.staff_id as staff_id,
+		avg(r.return_date::date - r.rental_date::date) as rental_duration
+	from rental r
+	group by r.staff_id
+	)
+select s.full_name,
+	s.address,
+	t.clientes,
+	r.rental_duration
+from top_employer t
+left join sub_address s
+	on t.staff_id = s.staff_id
+left join rental_duration r
+	on r.staff_id = s.staff_id
+
+