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Easy (I hope) join question


Easy (I hope) join question

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taigovinda
taigovinda
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Good point... For the sample data that is definitely smarter. In my actual data I have about 6 fields that are like 'address' in that there could be multiple distinct values and I only want to pick one - I suppose I could put min() for each one but that would probably be more expensive, right?
Sean Lange
Sean Lange
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taigovinda (8/2/2013)
Good point... For the sample data that is definitely smarter. In my actual data I have about 6 fields that are like 'address' in that there could be multiple distinct values and I only want to pick one - I suppose I could put min() for each one but that would probably be more expensive, right?


Actually MIN would be less expensive than using Row_Number. Since you say you only want to pick one, you have to either make a decision about the rules for which one or get a random one.

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taigovinda
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Thanks!
Jeff Moden
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taigovinda (8/2/2013)
Good point... For the sample data that is definitely smarter. In my actual data I have about 6 fields that are like 'address' in that there could be multiple distinct values and I only want to pick one - I suppose I could put min() for each one but that would probably be more expensive, right?


Careful... if you put MIN on each column, you could end up having Detroit in California. ;-)

--Jeff Moden

RBAR is pronounced ree-bar and is a Modenism for Row-By-Agonizing-Row.
First step towards the paradigm shift of writing Set Based code:
Stop thinking about what you want to do to a row... think, instead, of what you want to do to a column.
If you think its expensive to hire a professional to do the job, wait until you hire an amateur. -- Red Adair

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taigovinda
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Thanks for realizing that I needed that caution!

(I had to test the code that Lowell provided in order to understand that the same address would not be returned for both rows. I see, hopefully correctly, that it is the group by which ensures Mike doesn't get Tai's address but would not prevent mismatches within one person's distinct addresses...)
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