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need help and getting unique set Expand / Collapse
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Posted Tuesday, August 20, 2013 7:15 PM


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I didn't realize that brute force was allowed.

CREATE TABLE #temp
( set_id INT
,product CHAR(5)
,attribute INT)

INSERT INTO #temp (set_id, product, attribute) VALUES (1,'A',10) ,(1,'A',11)
INSERT INTO #temp (set_id, product, attribute) VALUES (2,'A',10),(2,'A',12)
INSERT INTO #temp (set_id, product, attribute) VALUES (3,'A',10),(3,'A',11);
INSERT INTO #temp (set_id, product, attribute) VALUES (4,'A',10),(4,'A',11);
INSERT INTO #temp (set_id, product, attribute) VALUES (5,'A',10),(5,'A',12);
INSERT INTO #temp (set_id, product, attribute) VALUES (6,'A',10),(6,'A',12),(6,'A',13);

DECLARE @setid INT = 1, @maxid INT = (SELECT MAX(set_id) FROM #temp);

-- Gotta start somewhere
SELECT * INTO #temp2 FROM #temp WHERE set_id = @setid;

WHILE @setid < @maxid
BEGIN
SELECT @setid = @setid + 1;

INSERT INTO #temp2
SELECT *
FROM #temp
WHERE set_id = @setid AND EXISTS (
SELECT product, attribute
FROM #temp
WHERE set_id = @setid
EXCEPT
SELECT product, attribute
FROM #temp2
GROUP BY set_id, product, attribute
);
END

SELECT * FROM #temp2 ORDER BY set_id, product, attribute;

GO
DROP TABLE #temp;
DROP TABLE #temp2;





My mantra: No loops! No CURSORs! No RBAR! Hoo-uh!

My thought question: Have you ever been told that your query runs too fast?

My advice:
INDEXing a poor-performing query is like putting sugar on cat food. Yeah, it probably tastes better but are you sure you want to eat it?
The path of least resistance can be a slippery slope. Take care that fixing your fixes of fixes doesn't snowball and end up costing you more than fixing the root cause would have in the first place.


Need to UNPIVOT? Why not CROSS APPLY VALUES instead?
Since random numbers are too important to be left to chance, let's generate some!
Learn to understand recursive CTEs by example.
Splitting strings based on patterns can be fast!
Post #1486485
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