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

From: Dave <David.C.Watson_at_gmail.com>
Date: 3 Mar 2007 19:43:43 -0800
Message-ID: <1172979823.606288.278530@s48g2000cws.googlegroups.com>


There will be 4 columns in the result 2 from table a and then two from table b... If you want to pick and choose the columns then do so in the select statement...

SELECT a.col1, a.col2, b.col3
FROM ... On Mar 2, 10:07 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
Received on Sat Mar 03 2007 - 21:43:43 CST

Original text of this message

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