I have a question, I am trying to list all of the actors for each movie in my database. Right now I have this SQL
SELECT title, count(1) COUNT, actor.first_name, actor.last_name
FROM film
INNER JOIN film_actor ON film.film_id = film.actor.film_id
INNER JOIN actor ON film_actor.actor_id = actor.actor_id
GROUP BY title.
What I am trying to do is format my out put into a text file like this:
Title:Number of Actors in each film: Actor first name(1): Actor last name(2) : Actor first name(2): Actor last name(2) ... ect
But for example, in the first film there are ten actots for this film. How would I print out the first and last name of each actor for each movie.
The problem is you want aggregate and non-aggregate data.
One way to achieve this in MySQL you would have to get the count of actors in each film as a sub query and join back to the base set.
SELECT title, b.cnt COUNT, actor.first_name, actor.last_name
FROM film
INNER JOIN film_actor
ON film.film_id = film_actor.film_id
INNER JOIN actor
ON film_actor.actor_id = actor.actor_id
INNER JOIN (SELECT film_ID, count(1) as cnt
FROM film_actor
GROUP BY film_ID) B
on film.film_ID = B.Film_ID
in databases which support window functions you could use a count(1) over (parttition by film.film_ID) as cnt
It may also be able to be achieved by using a group by with rollup without using an added join; but this creates an additional row with the total.
SELECT title, count(1) COUNT, actor.first_name, actor.last_name
FROM film
INNER JOIN film_actor
ON film.film_id = film_actor.film_id
INNER JOIN actor
ON film_actor.actor_id = actor.actor_id
on film.film_ID = B.Film_ID
GROUP BY title with rollup
Related
"Determine if there are actors with the same first name who appeared in the same movie."
This is my task and I'm supposed to do that with subqueries and I just dont really know what else to do. I tried everything with group by, order by and having count but I just don't get to the point where I get the same first name actors with the same movie.
Maybe someone can help me? I am using Sakila Database
SELECT
a.first_name
,(a.last_name)
,a.actor_id
, f.title
FROM actor a
JOIN film_actor fa ON fa.actor_id = a.actor_id
JOIN film f ON f.film_id = fa.film_id
JOIN(SELECT b.first_name, COUNT(*)
FROM actor B
GROUP BY b.first_name
HAVING COUNT(*) > 1 ) b
ON a.first_name = b.first_name
GROUP BY a.last_name
HAVING COUNT(f.title) > 1
ORDER BY a.first_name
You can do this with joins only:
select f.title, a1.first_name, a1.last_name as last_name_1, a2.last_name as last_name_2
from film f
inner join film_actor fa1 on fa1.film_id = f.film_id
inner join film_actor fa2 on fa2.film_id = f.film_id
inner join actor a1 on a1.actor_id = fa.actor_id
inner join actor a2 on a2.actor_id = fa.actor_id
where a1.first_name = a2.first_name and a1.actor_id < a2.actor_id
Starting from the film table, this follows the relationships to actor through film_actor twice, and then filters on diffrerent actors that have the same first name.
As a result, you get tuples of actors that have the same last name and played in the same film. The inequality condition ensures that there are no "mirror" records (that is, each tuple appears only once per film).
I would simply use aggregation:
SELECT fa.film_id, a.first_name,
GROUP_CONCAT(a.last_name) as last_names,
GROUP_CONCAT(a.actor_id) as actor_ids
FROM actor a JOIN
film_actor fa
ON fa.actor_id = a.actor_id
GROUP BY fa.film_id, a.first_name
HAVING COUNT(*) > 1;
Your question doesn't specify what the result set should look like. This returns one row per actors with the same first name in a film. The last names are concatenated into a string as are the actor ids.
How about this:
SELECT f.title, f.film_id, a.first_name, a.last_name, a.actor_id
FROM actor a
JOIN film_actor fa ON fa.actor_id = a.actor_id
JOIN film f ON f.film_id = fa.film_id
WHERE a.first_name IN (
SELECT a2.first_name
FROM actor a2
JOIN film_actor fa2 ON fa2.actor_id = a2.actor_id
JOIN film f2 ON f2.film_id = fa2.film_id
WHERE a2.actor_id <> a.actor_id AND f2.film_id = f.film_id
)
ORDER BY f.title ASC, a.last_name ASC, a.first_name ASC
Explaining query step-by-step
SELECT the needed fields from the joined tables
JOIN the necessary tables
WHERE (here is the subquery) a.first_name is in the set of:
firstnames of actors, different than the current actor (a2.actor_id <> a.actor_id) and the film is the same (f2.film_id = f.film_id)
The subquery in where is a similar select with joins query as the parent query.
PS:
One can do variations on this basic query template:
Eg film_id can be given as parameter, so one can find all actors with same name for specific film.
Also one can group and count how many actors appeared in same film wih same name eg by grouping on film_id and counting.
One can even optimise a bit the query by removing unnecessary joins (eg film.title may not be needed at all) and so on..
The advantage of having single results returned (instead of tuples or aggregates) is that number of actors with same name in same film is not fixed and manipulating the results, eg by grouping and counting or getting further info for each actor, is easier.
The price is a slightly more complex and potentialy slower query.
With this query I display the year field, the first record in ASC order, and the last in DESC order.
Works well if the year field is different
example:
1960-1970
but if the field is the same
example:
1960
I see duplicate
1960 - 1960
I would only like to see once
1960
how to do?
$query = "(SELECT
year as year_asc
FROM film_actor
INNER JOIN film ON film_actor.film_id = film.film_id
INNER JOIN actor ON film_actor.actor_id = actor.actor_id
WHERE film_actor.actor_id = $actor_id
ORDER BY year ASC
LIMIT 1)
UNION ALL
(SELECT
year as year_desc
FROM film_actor
INNER JOIN film ON film_actor.film_id = film.film_id
INNER JOIN actor ON film_actor.actor_id = actor.actor_id
WHERE film_actor.actor_id = $actor_id
ORDER BY year DESC
LIMIT 1)";
you may use UNION, rather than UNION ALLsince UNION will eliminate duplicates.
If you want the minimum and maximum years, you can put them in a single query:
SELECT MIN(year) as min_year, MAX(year) as max_year
FROM film_actor fa JOIN
film f
ON fa.film_id = f.film_id JOIN
actor a
ON fa.actor_id = a.actor_id
WHERE fa.actor_id = $actor_id;
If you want a single column, perhaps with a hyphen, you can use:
SELECT CONCAT_WS('-', MIN(YEAR), NULLIF(MAX(YEAR), MIN(YEAR)))
I am trying to find the correct SQL to perform my task. I am trying to find the count of all actors that all act in the same movie. For all the movies. My SQL statement to fetch the film title and the first and last name of each actor is.
SELECT title, actor.first_name, actor.last_name,
FROM film
INNER JOIN film_actor ON film.film_id = film_actor.film_id
INNER JOIN actor ON film_actor.actor_id = actor.actor_id
ORDER BY film.title
My database returns this :
As you can see there are 10 actors belonging to the movie title ACADEMY DINOSAUR. What is the SQL that would provide me with a number of actors for each film?
Your SQL can be like this
SELECT title, count(1) COUNT
FROM film
INNER JOIN film_actor ON film.film_id = film_actor.film_id
INNER JOIN actor ON film_actor.actor_id = actor.actor_id
GROUP BY title
Pls try this
select tt.title, count(1) from (
SELECT title, actor.first_name, actor.last_name,
FROM film
INNER JOIN film_actor ON film.film_id = film_actor.film_id
INNER JOIN actor ON film_actor.actor_id = actor.actor_id
) tt group by tt.title
ORDER BY tt.title
I am writing a query to give actor id, first name, and last name for all actors who have never appeared in a film rated ‘PG’.
Here is what I've done. Can anyone tell me what I did wrong, please?
select distinct actor.actor_id, actor.first_name, actor.last_name
from actor, film, film_actor
where NOT exists
(Select distinct actor.actor_id,actor.first_name,actor.last_name
from actor,film_actor,film
where actor.actor_id = film_actor.actor_id
and film_actor.film_id = film.film_id
and film.rating = 'PG');
The not exists test for a condition and if the condition is true (exists) return false (not exists)
then in you case you get correctly no result
could be you need the actors not in you select
select actor.actor_id, actor.first_name, actor.last_name
from actor
where actor.id NOT in
(Select distinct actor.actor_id
from actor,film_actor,film
where actor.actor_id = film_actor.actor_id
and film_actor.film_id = film.film_id
and film.rating = 'PG');
Following up from the answer above, the line "actor.actor_id = film_actor.actor_id" inside the nested query is not necessary to get the same results. Shorter version:
select distinct a.actor_id, a.first_name, a.last_name from actor a where actor_id NOT IN (select distinct fa.actor_id from film_actor fa, film f where fa.film_id = f.film_id AND f.rating = 'PG');
Using: http://dev.mysql.com/doc/sakila/en/
I'm trying to write a query to count the number of films each actor has acted in by category.
Would appreciate any pointers or advice.
Here is my code so far (it counts the films correctly for one category when I take out the second LEFT JOIN section):
SELECT actor.first_name, actor.last_name,
COUNT(subset.film_id) AS action,
COUNT(subset2.film_id) AS animation
FROM actor
LEFT JOIN (
SELECT film.film_id, actor.actor_id
FROM actor
INNER JOIN film_actor
ON film_actor.actor_id = actor.actor_id
INNER JOIN film
ON film.film_id = film_actor.film_id
INNER JOIN film_category
ON film_category.film_id = film.film_id
INNER JOIN category
ON category.category_id = film_category.category_id
WHERE category.name = 'Action') AS subset
ON subset.actor_id = actor.actor_id
LEFT JOIN (
SELECT film.film_id, actor.actor_id
FROM actor
INNER JOIN film_actor
ON film_actor.actor_id = actor.actor_id
INNER JOIN film
ON film.film_id = film_actor.film_id
INNER JOIN film_category
ON film_category.film_id = film.film_id
INNER JOIN category
ON category.category_id = film_category.category_id
WHERE category.name = 'Animation') AS subset2
ON subset2.actor_id = actor.actor_id
GROUP BY actor.actor_id
ORDER BY actor.last_name ASC;
The query you've got seems awfully complicated if all you want is to get a count of movies per actor and category.
This query:
SELECT
actor.first_name, actor.last_name, category.name,
COUNT(*) as CountPerCategory
FROM actor
JOIN film_actor ON film_actor.actor_id = actor.actor_id
JOIN film ON film.film_id = film_actor.film_id
JOIN film_category ON film_category.film_id = film.film_id
JOIN category ON category.category_id = film_category.category_id
GROUP BY actor.first_name, actor.last_name, category.name;
would give you an output like:
Firstname, Lastname, Category, CountPerCategory
Clint Eastwood Animation 1
Clint Eastwood Action 15
but if you want the counts per category in different columns you could exploit the fact that MySQL returns 1 for true conditions and test that the category matches and use sum (this could also be don't with a case expression in a more portable way), like this:
SELECT
actor.first_name, actor.last_name, category.name
, SUM(category.name = 'Animation') as CountOfAnimation
, SUM(category.name = 'Action') as CountOfAction
FROM actor
JOIN film_actor ON film_actor.actor_id = actor.actor_id
JOIN film ON film.film_id = film_actor.film_id
JOIN film_category ON film_category.film_id = film.film_id
JOIN category ON category.category_id = film_category.category_id
GROUP BY actor.first_name, actor.last_name, category.name;
which would give a result like:
Firstname, Lastname, CountOfAnimation, CountOfAction
Clint Eastwood 1 15
Note that if a film belongs to multiple categories it would get counted once for each category, which might be what you want (or not).
This should give you the count for all actors, with all categories they have been associated with:
SELECT actor.first_name, actor.last_name, category.name
, COUNT(DISTINCT film.film_id)
FROM actor
LEFT JOIN film_actor ON film_actor.actor_id = actor.actor_id
LEFT JOIN film ON film.film_id = film_actor.film_id
LEFT JOIN film_category ON film_category.film_id = film.film_id
LEFT JOIN category ON category.category_id = film_category.category_id
GROUP BY actor.first_name, actor.last_name, category.name
;
If you only want specific ones, add on this after the GROUP BY line:
HAVING category.name IN ('Action', 'Animation')
If you only want actors with those categories, change the LEFT JOINs to INNER JOINs and/or change the aforementioned HAVING to a WHERE (and reposition it accordingly).
I agree, that query looks very complicated and by using 2 derived tables it'll probably run slowly as well. This query will give the unique films in each category and will not duplicate the results as there are no many to many joins.
It will slow down as you add categories however because it has to scan the table multiple times but it will give accurate results and as long as your table isn't too large it should be fine.
You probably don't need the distinct's, but if for whatever reason someone had the same category on a film twice (or something similar) this will remove room for error.
select a.first_name, a.last_name
, (
select count(distinct f.id)
from film f
join film_actor fa on fa.film_id=f.film_id
join film_category fc on fc.film_id=f.film_id
join category c ON c.category_id = fc.category_id
where c.name='Animation'
and fa.actor_id=a.actor_id
) as unique_animation_films
, (
select count(distinct f.id)
from film f
join film_actor fa on fa.film_id=f.film_id
join film_category fc on fc.film_id=f.film_id
join category c ON c.category_id = fc.category_id
where c.name='Action'
and fa.actor_id=a.actor_id
) as unique_action_films
from actor a