SQL JOINS

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SQL JOINS

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Raghavendra Mudugal SSChampion Points: 10658 More actions · Answer 1

Koen Verbeeck (1/8/2013)
Not sure what this question tries to teach us....

I guess.. this; if the aliases are been removed in SELECT block, it gives below error on ambiguity for couple of column names. (some sort.... author might had in mind)

Msg 209, Level 16, State 1, Line 3

Ambiguous column name 'Name2'.

Msg 209, Level 16, State 1, Line 4

Ambiguous column name 'Name3'.

(looks like this was one of the "out of the box" experience 🙂 )

ww; Raghu
--
The first and the hardest SQL statement I have wrote- "select * from customers" - and I was happy and felt smart.

Dana Medley SSCertifiable Points: 6764 More actions · Answer 2

Koen Verbeeck (1/8/2013)
Not sure what this question tries to teach us.
I spend 5 minutes looking for a mistake, only to finally decide there wasn't one, all joins seemed legit. I got it right, but I suddenly was surprised the question was about table aliases.

I'm with Koen on this one. I spent a few minutes (I think more than 5) analyzing the queries and looking for that "gotcha" that sticks out once you find it, but no such luck on that.

Everything is awesome!

Keld Laursen (SEGES) SSC Eights! Points: 843 More actions · Answer 3

I concur with many here. It were somewhat of a disappointment to end up with some alias-stuff after spending quite some time looking for the column not being aggregated, or, as I thought first, some union with disparaging column definitions or some such. But no, just straight aliasing.

I am quite used to aliasing a lot of tables, and also making sure to get the right columns from the right tables when the names clashes, så the alias stuff were the last thing on my mind.

But thank you for the question anyway. A good friday question, even on a wednesday 🙂

/Keld

mtassin SSC-Insane Points: 23099 More actions · Answer 4

Koen Verbeeck (1/8/2013)
Not sure what this question tries to teach us.
I spend 5 minutes looking for a mistake, only to finally decide there wasn't one, all joins seemed legit. I got it right, but I suddenly was surprised the question was about table aliases.

Same here... and since we went to wide short monitors I had to keep scrolling up and down to make sure I could keep the entire schema in my head.

Koen Verbeeck (1/8/2013)
Maybe I was more surprised that apparently the criteria for a query to run succesfully is to get your table aliases correct 🙂

Among other things 🙂

--Mark Tassin
MCITP - SQL Server DBA
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Revenant SSC-Forever Points: 42467 More actions · Answer 5

Thanks for an easy question.

However, I noticed then if the QotD offers choice 'this will run' and 'this will not run', in most cases the answer is 'it will', so the question is reduced to 'is there an egregious problem?'. Which takes a good deal of fun out of figuring out the correct answer.

chgn01 SSCarpal Tunnel Points: 4354 More actions · Answer 6

Thanks for all comments. we use aliases in joins. Aliases are not for columns where there is only one column possible. But it is nice to have all aliases listed just for maintainability in joins.

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;-)“Everything has beauty, but not everyone sees it.” ― Confucius

SQLRNNR SSC Guru Points: 281334 More actions · Answer 7

sqlnaive (1/9/2013)
Dineshbabu (1/8/2013)
Andre Ranieri (1/8/2013)
Nice question - I wonder if the question category should have been table aliases instead of joins 🙂
Thanks,
Andre Ranieri
+1
I agree with both Andre and Dineshbabu. Was looking for any issues in the joins for couple of minutes but found no issues.

+1

Jason...AKA CirqueDeSQLeil
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Toreador SSChampion Points: 11365 More actions · Answer 8

chgn01 (1/9/2013)
Aliases are not for columns where there is only one column possible.

Whyever not?

OCTom SSChampion Points: 11785 More actions · Answer 9

chgn01 (1/9/2013)
Thanks for all comments. we use aliases in joins. Aliases are not for columns where there is only one column possible. But it is nice to have all aliases listed just for maintainability in joins.

For my learning... how does using aliases affect maintainability?

Thanks,

Tom

Miles Neale SSChampion Points: 13147 More actions · Answer 10

Nice, had to think about it far a few minutes but got it.

Thanks

Not all gray hairs are Dinosaurs!

Rob Schripsema SSCertifiable Points: 7469 More actions · Answer 11

Revenant (1/9/2013)
Thanks for an easy question.
However, I noticed then if the QotD offers choice 'this will run' and 'this will not run', in most cases the answer is 'it will', so the question is reduced to 'is there an egregious problem?'. Which takes a good deal of fun out of figuring out the correct answer.

Agreed.

Rob Schripsema
Propack, Inc.

jvac SSC Journeyman Points: 94 More actions · Answer 12

Good question, got it! Thanks

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