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Re: Which column is taken in JOIN with multiple columns and different content ?

From: Anurag Varma <avoracle_at_gmail.com>
Date: 2 Mar 2007 09:22:46 -0800
Message-ID: <1172856166.492000.176350@8g2000cwh.googlegroups.com>


On Mar 2, 11:07 am, mer..._at_gmx.net (Tobias Merler) wrote:
> Assume I join two tables.
> Both of these tables contain a column with name "col1". This column ist not he primary key.
> However this column contains different values which value is taken ?
>
> Lets see the following example:
>
> Select *
> FROM tablea a, tableb b
> Where a.id = b.id
>
> tablea:
>
> id col1 col2
>
> 1 aaa ddd
> 2 bbb eee
> 3 ccc fff
>
> tableb:
>
> id col1 col3
>
> 1 zzz uuu
> 2 xxx vvv
> 3 yyy www
>
> The result table will look like:
>
> id col1 col2 col3
>
> 1 ??? ddd uuu
> 2 ??? eee vvv
> 3 ??? fff www
>
> Which values will be for the questions marks ?
>
> Ok, I know the data model is not perfect and the two tables could be merged.
> But keep in mind that the sample is only a simplified version of a more complex
> SQL statement. So lets concentrate on my question.
>
> Thank you
>
> Toby

I'm kinda interested in what you think would happen? Also, I'm extremely curious to know why you cannot test this yourself?

And if I tell you a hooey answer like "Oracle will know what column you
want and give that to you. You know .. thats why its called Oracle" .. would you believe me and not test it yourself?

There is no substitute to testing a problem yourself.

Anurag Received on Fri Mar 02 2007 - 11:22:46 CST

Original text of this message

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