WHERE (set) IN (set) - mysql

Question

EDIT: I seemed to have asked this question incorrectly.
I'm trying to find a way to query if a set is available in another set. For example:
SELECT * FROM something
WHERE (1, 3) IN (1, 2, 3, 4, 5)
In this case, 1 & 3 are in the set (1, 2, 3, 4, 5). Another example:
SELECT * FROM something
WHERE (1, 3) IN (1, 5, 7, 9);
In this case, 1 & 3 ARE NOT in the set (1, 5, 7, 9) so nothing should be pulled from the table.

Answer 1

NOTE: This answers the original question, which seems to have nothing to do with the question after OP modifications.
You can get the users who completed all three levels by using:
SELECT cl.user_id
FROM completed_levels cl
WHERE cl.id IN (3, 5, 7)
GROUP BY cl.user_id
HAVING COUNT(DISTINCT cl.id) = 3;
(Note: DISTINCT is not necessary if the ids for a given user are unique.)
THEN, you can get what you want using a JOIN or similar construct:
SELECT u.*
FROM users u JOIN
(SELECT cl.user_id
FROM completed_levels cl
WHERE cl.id IN (3, 5, 7)
GROUP BY cl.user_id
HAVING COUNT(DISTINCT cl.id) = 3
) cu
ON cl.user_id = u.id;

Answer 2

NEW REQUEST (according to sqlfiddle.com/#!9/f36d92/2):
# The goal is to write a query that will select all exercises
# that the user has the correct equipment for, where the pre-defined
# set is the id's of the equipment the user has.
# For example, let's assume the user has equipment (1, 4)
# The exercise "Curls" should be pulled from the table, as the user has all
# of the required equipment based on the exercise_requirements table.
# while "Wrecking Ball" is not returned as the user only has a portion of the
# required equipment.
# If the user's equipment was (1, 3, 4) then both "Curls" and "Wrecking ball"
# would be returned from the exercises table, as the user has the required equipment
# for both exercises.
#----
#Below is my take on your query.
SELECT ex.* FROM exercises ex
WHERE ex.id IN (
SELECT exercise_id FROM exercise_requirements
WHERE ex.id IN (1, 4)
GROUP BY exercise_id
HAVING COUNT(distinct exercise_id) = 3
);
SOLUTION:
You are confusing some IDs here. This would be closer:
SELECT ex.* FROM exercises ex
WHERE ex.id IN (
SELECT exercise_id FROM exercise_requirements
WHERE equipment_id IN (1, 4)
GROUP BY exercise_id
HAVING COUNT(distinct equipment_id) = 2
);
But still this query is vice versa. We don't want to know whether all the user's equipment are found in a set of equipment needed for an exercise, but whether the whole set of equipment needed for an exercise is found in the user's equipment.
Probably the easiest way to write this is: aggregate exercise_requirements per exercise_id and check that no equipment_id is needed that the user doesn't have.
select *
from exercises
where id in
(
select exercise_id
from exercise_requirements
group by exercise_id
having sum(equipment_id not in (1, 4)) = 0
);
Your updated fiddle: http://sqlfiddle.com/#!9/f36d92/5

Answer 3

You are using the IN clause with a correlated subquery (i.e. the subquery references u.id). This is not how we use it. The IN clause is great for non-correlated subqueries; if you need a correlated subquery, use EXISTS instead. For your problem a non-correlated subquery suffices, so use IN accordingly:
select *
from users
where u.id in (select user_id from completed_levels where id in (1, 5, 7);
If a user must have all levels:
select *
from users
where u.id in (select user_id from completed_levels where id = 1
and u.id in (select user_id from completed_levels where id = 5
and u.id in (select user_id from completed_levels where id = 7;
Such problems are usually better solved with an aggregation so as not to have to query the same table again and again:
select *
from users
where u.id in
(
select user_id
from completed_levels where id in (1, 5, 7)
group by user_id
having count(distinct id) = 3
);

Answer 4

You could use this
SELECT u.*
FROM users u
INNER JOIN completed_levels cl
ON cl.user_id = u.id
WHERE cl.id IN (1, 5, 7);
Or using EXISTS as link from #DanFromGermany

Answer 5

You can use Case to make a Sum which will increase with 1 for each level within 1, 5 & 7.
SELECT A.* FROM users AS
INNER JOIN
(
SELECT U.id,
SUM(CASE WHEN
(
A.completed_levels = 1
OR A.completed_levels = 5
OR A.completed_levels = 7
) THEN 1 ELSE 0 END
) AS RN
FROM completed_levels A
INNER JOIN users U ON A.user_id = U.id
GROUP BY U.id
) B ON A.id = B.id
WHERE B.RN = 3 -- Those users have completed level 1, 5 & 7 will have RN = 3 only