select [CAR] based on [FEATURE]s -- all or nothing - sql

Question

Currently, I have 2 tables with the following data:
[CAR]
Honda
Ford
Mazda
[FEATURE]
CD player
Sunroof
Leather
In another table, I store their relationships.
[CAR_FEATURE]
Honda | CD Player
Mazda | CD Player
Mazda | Sunroof
Mazda | Leather
My problem is... I need to select the [CAR] that has all the [FEATURE] I am looking for -- all or nothing.
For example, if I am looking for a car with a CD Player, Sunroof, AND Leather, then it would output Mazda.
If I am looking for a car with a CD Player, then it would ONLY output Honda.
If I am looking for a car with a Sunroof, then it would output nothing because I am searching for all or nothing.
How would I write the query statement in SQL for this particular case?

Answer 1

This variation of T McKeown's query will get you a car matching all the features exactly, not more or less:
SELECT CAR
FROM CAR_FEATURE
GROUP BY CAR
HAVING SUM(CASE WHEN FEATURE IN ('CD Player', 'Sunroof', 'Leather')
THEN 1
ELSE -1
END) = 3

Answer 2

This would work:
SELECT CAR
FROM CAR_FEATURE
WHERE FEATURE IN ('CD Player', 'Sunroof', 'Leather')
GROUP BY CAR
HAVING COUNT(*) = 3
Just adjust the HAVING clause based on the features, you could pass in a CSV list of features and create a TABLE variable table that has all the features so the query could be like this:
DECLARE #LIST_OF_FEATURES TABLE(FEATURE VARCHAR(50))
--INSERT INTO THE #LIST_OF_FEATURES USING THE FORXML
SELECT CAR
FROM CAR_FEATURE
WHERE FEATURE IN (SELECT FEATURE FROM #LIST_OF_FEATURES)
GROUP BY CAR
HAVING COUNT(*) = (SELECT COUNT(*) FROM #LIST_OF_FEATURES)

Answer 3

I don't know the exact table structure, so I will improvise with field names. I hope it's clear from context:
SELECT c.*
FROM CAR c
JOIN CAR_FEATURE cf ON (c.id = cf.car_id)
JOIN FEATURE f ON (f.id = cf.feature_id)
LEFT JOIN FEATURE f2 ON (f2.id = cf.feature_id
AND f2.id NOT IN (<list of feature ids>))
WHERE f.id IN (<same list of features ids as above>)
AND f2.id IS NULL
This would bring the cars that have the features you want, but that do not have any other features.
Concrete example. Suppose your feature id are the names (not a great idea, but good for the example), then you would write:
SELECT c.*
FROM CAR c
JOIN CAR_FEATURE cf ON (c.id = cf.car_id)
JOIN FEATURE f ON (f.id = cf.feature_id)
LEFT JOIN FEATURE f2 ON (f2.id = cf.feature_id
AND f2.id NOT IN ('CD Player','Sunroof'))
WHERE f.id IN ('CD Player','Sunroof')
AND f2.id IS NULL
Hope this helps!