How to retrieve unique rows where multiple children that reference it exist for different types? - sql

Question

SELECT * FROM Fruit
INNER JOIN Apple ON Fruit.Id = Apple.FruitId
WHERE Apple.Type = 1 AND Apple.Type = 3
I need to get unique rows of Fruit that have both Apples that are of type 1 AND 3. Apple.Type is considered unique, but I wouldn't think it matters though.
With these rows, this should return two rows with both Fruit #50 and #52. The most important part is the Fruit.Id, I don't need to return the Types, but just need to make sure every single Fruit returned has at least one Apple.Type = 1 and one Apple.Type = 3.
Apple { Id = 1, FruitId = 50, Type = 0 }
Apple { Id = 2, FruitId = 50, Type = 1 }
Apple { Id = 3, FruitId = 50, Type = 3 }
Apple { Id = 4, FruitId = 51, Type = 1 }
Apple { Id = 5, FruitId = 51, Type = 2 }
Apple { Id = 6, FruitId = 52, Type = 3 }
Apple { Id = 7, FruitId = 52, Type = 1 }
Apple { Id = 8, FruitId = 52, Type = 2 }
Fruit { Id = 50 }
Fruit { Id = 51 }
Fruit { Id = 52 }
I'm not quite sure how to use DISTINCT and/or GROUP BY in order to form this query.

Answer 1

Group your apples table by fruit id and pick the results that have both desired types. Use this to get your fruits.
SELECT *
FROM Fruit
WHERE id IN
(
SELECT FruitId
FROM Apple
WHERE Type IN (1,3)
GROUP BY FruitId
HAVING COUNT(DISTINCT Type) = 2
);

Answer 2

This would return the fruits with ID 50 and 52.
SELECT *
FROM Fruit
WHERE EXISTS (
SELECT 1 FROM Apple
WHERE Type = 1 AND Apple.FruitId = Fruit.Id
) AND EXISTS (
SELECT 1 FROM Apple
WHERE Type = 3 AND Apple.FruitId = Fruit.Id
)

Answer 3

Not the most efficient way, but transposing those columns out so you have multiple types per fruitid should do it.
create table type_1 as select FruitId, Type as Type1 from Apple where Type = 1;
create table type_3 as select FruitId, Type as Type3 from Apple where Type = 3;
create table Fruits as select distinct FruitId from Apple;
create table Fruit_Agg as select a.FruitId, b.Type1, c.Type3 from Fruits a left join type_1 b on a.FruitId = b.FruitId left join type_3 c on a.FruitId = c.FruitId;
create table Types_1and_3 as select FruitId from Fruit_Agg where Type1 = 1 and Type3 = 3;