SQL-Query - finding pattern of another table - sql

Question

I have a table with colors:
COLORS
idColor Name
------- ------
4 Yellow
5 Green
6 Red
And I have another table with data:
PRODUCTS
idProduct idCategory idColor
--------- ---------- -------
1 1 4
2 1 5
3 1 6
4 2 10
5 2 11
6 2 12
7 3 4
8 3 5
9 3 8
10 4 4
11 4 5
12 4 6
13 5 4
14 6 4
15 6 5
I just want return rows from Products when the idColor values from table Colors (4, 5, 6) are present in the second table and IdCategory has exactly 3 elements with the same idColor values 4, 5, 6.
For this example, The query should return:
IdCategory
----------
1
4

Answer 1

Try this:
SELECT idCategory
FROM PRODUCTS
GROUP BY idCategory
HAVING COUNT(*) = 3
AND COUNT(DISTINCT CASE WHEN idColor IN (4,5,6) THEN idColor END) = 3
Here is a demo for you to try.
UPDATED
If you want to dynamically filter the results depending on the values of the table `COLOR
SELECT idCategory
FROM PRODUCTS P
LEFT JOIN (SELECT idColor, COUNT(*) OVER() TotalColors
FROM COLORS) C
ON P.idColor = C.idColor
GROUP BY idCategory
HAVING COUNT(*) = MIN(C.TotalColors)
AND COUNT(DISTINCT C.idColor) = MIN(C.TotalColors)
Here is a fiddle with this example.

Answer 2

You can use aggregates to make sure it has all 3 colors, and also to make sure it DOESN'T have any other colors. Something like this:
SELECT *
FROM
(
SELECT idCategory
, SUM(CASE WHEN idColor IN (4, 5, 6) THEN 1 ELSE 0 END) AS GoodColors
, SUM(CASE WHEN idColor NOT IN (4, 5, 6) THEN 1 ELSE 0 END) AS BadColors
FROM Products
GROUP BY idCategory
) t0
WHERE GoodColors = 3 AND BadColors = 0
Note, if the 4, 5, 6 is found more than once per idCategory then a different technique must be employed. But from your example, it doesn't appear that way.

Answer 3

I am guessing that you would like to perform this task based on data in a table, rather than hardcoding the values 4, 5, and 6 (like in some of the answers given). To that end, in my solution I created a dbo.ColorSets table that you can fill with as many different sets of colors as you want, then run the query and see all the product Categories that match those color Sets. The reason I didn't just use your dbo.Color table is that it appeared to be the lookup table, complete with color names, so it didn't seem like the right one to be picking out a particular set of colors rather than the entire list possible.
I used a technique that will maintain good performance even on huge amounts of data, as compared to other query methods that use aggregates exclusively. No matter what method one uses, this task will pretty much always require a scan of the entire Products table because you can't compare all the rows without, well, comparing all the rows. But the JOIN is on indexable columns and is only for the candidates that have a very good chance of being proper matches, so the amount of work required is greatly reduced.
Here's what the ColorSets table looks like:
CREATE TABLE dbo.ColorSets (
idSet int NOT NULL,
idColor int NOT NULL,
CONSTRAINT PK_ColorSet PRIMARY KEY CLUSTERED (idSet, idColor)
);
INSERT dbo.ColorSets
VALUES
(1, 4),
(1, 5),
(1, 6), -- your color set: yellow, green, and red
(2, 4),
(2, 5),
(2, 8) -- an additional color set: yellow, green, and purple
;
And the query (see this working in a SqlFiddle):
WITH Sets AS (
SELECT
idSet,
Grp = Checksum_Agg(idColor)
FROM
dbo.ColorSets
GROUP BY
idSet
), Categories AS (
SELECT
idCategory,
Grp = Checksum_Agg(idColor)
FROM
dbo.Products
GROUP BY
idCategory
)
SELECT
S.idSet,
C.idCategory
FROM
Sets S
INNER JOIN Categories C
ON S.Grp = C.Grp
WHERE
NOT EXISTS (
SELECT *
FROM
(
SELECT *
FROM dbo.ColorSets CS
WHERE CS.idSet = S.idSet
) CS
FULL JOIN (
SELECT *
FROM dbo.Products P
WHERE P.idCategory = C.idCategory
) P
ON CS.idColor = P.idColor
WHERE
CS.idColor IS NULL
OR P.idColor IS NULL
)
;
Result:
idSet idCategory
1 1
2 3
1 4

Answer 4

If I understand your question, this should do it
select distinct idCategory
from Products
where idColors in (4,5,6)