Select unmatched data from two columns

Question

Post reply

Select unmatched data from two columns

Viewing 9 posts - 16 through 24 (of 24 total)

You must be logged in to reply to this topic. Login to reply

paul s-306273 SSChampion Points: 10730 More actions · Answer 1

paul s-306273

SSChampion

Points: 10730

November 26, 2012 at 7:57 am

#1562245

Interesting qotd.

Dana Medley SSCertifiable Points: 6764 More actions · Answer 2

So many words for a Monday morning question; I ended up reading it 4 or 5 times before answering. :hehe:

Thank you very much, it was a good one.

Everything is awesome!

Kick6Tiger SSCrazy Points: 2380 More actions · Answer 3

The oddity that I find interesting about this question is the fact that the UNION automatically sorts the results. In my head I'm thinking the results would be 4,7,2,8 and 2,8,4,7 from the two correct options.

***I now see that using the UNION ALL would not do the sorting to look for duplicates and would have given me the results that I expected.

Aigle de Guerre!

(Bob Brown) SSCrazy Points: 2705 More actions · Answer 4

(Bob Brown)

SSCrazy

Points: 2705

November 26, 2012 at 10:14 am

#1562306

Great question. Gave me something to think about.

Paul White SSC Guru Points: 150468 More actions · Answer 5

Meow Now (11/26/2012)
The oddity that I find interesting about this question is the fact that the UNION automatically sorts the results. In my head I'm thinking the results would be 4,7,2,8 and 2,8,4,7 from the two correct options.
***I now see that using the UNION ALL would not do the sorting to look for duplicates and would have given me the results that I expected.

It depends on the physical implementation of the UNION / UNION ALL by the query optimizer. Depending on your SQL Server version, you will / might see different results with e.g. OPTION (HASH UNION) or OPTION (MERGE UNION). As always, ORDER BY is required for output ordering guarantees 🙂

Paul White
All articles available on SQL.kiwi
@SQL_Kiwi