robert.gerald.taylor (9/19/2012)
Couldn't you just unpivot your data? Something like:
SELECT DISTINCT SpecificCols
FROM
(SELECT col1, col2, col3, col4
FROM @t) t
UNPIVOT
(SpecificCols FOR AllCols IN (col1, col2, col3, col4)) AS unpvt;
HTH,
Rob
There's a (usually) faster way:
SELECT col
FROM @t
CROSS APPLY (
VALUES (col1), (col2), (col3), (col4)) a(col)
This article describes the CROSS APPLY VALUES approach to UNPIVOT: http://www.sqlservercentral.com/Authors/Articles/Dwain_Camps/1444841/ including some information on the performance characteristics. More detailed performance results can be found in the associated discussion thread.
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?[/url]
Since random numbers are too important to be left to chance, let's generate some![/url]
Learn to understand recursive CTEs by example.[/url]
[url url=http://www.sqlservercentral.com/articles/St