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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.
Although they tell us that they want it real bad, our primary goal is to ensure that we dont actually give it to them that way.
Although change is inevitable, change for the better is usually not.
Just because you can do something in PowerShell, doesnt mean you should. Wink

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taigovinda
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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