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

merlin_at_gmx.net (Tobias Merler) wrote in
news:45e84bdf$0$23135$9b4e6d93_at_newsspool1.arcor-online.net:

> 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
>
>
>

Toby,
Because of the conflicting column names, Oracle would give you a syntax error, try it. The syntax in Oracle would be select a.*, b.*. The resulting table should be apparent now.

Andy Young Received on Fri Mar 02 2007 - 22:38:00 CST