Re: Two columns with same name in subselect--any way to SELECT without *?

On 01/06/2018 08:46 PM, Ken Tanzer wrote:
> Hi.  You can have multiple columns with the same name, and use it as a
> subselect, like this silly example:
>
> SELECT 'a' AS my_col,'b' AS my_col,'foo' AS other;
> SELECT * FROM (SELECT 'a' AS my_col,'b' AS my_col,'foo' AS other) foo;
>
> But is there any way to select either of those columns without taking
> all the fields with *?
>
> SELECT my_col,other FROM (select 'a' AS my_col,'b' AS my_col,'foo' AS other) foo;
> ERROR: column reference "my_col" is ambiguous
>
> I suspect there isn't, but just wondering if there's some way I'm not
> aware of.

?:
SELECT bar.my_col, foo.my_col FROM (SELECT 'a' AS my_col) as bar ,
(select 'b' AS my_col,'foo' AS other) foo;

my_col | my_col
--------+--------
a | b

Though I would think this would just be pushing the point where you get
confused what my_col is really pointing to down the road.

>
> I found myself wanting to specify the columns by position, similar to
> ORDER or GROUP. (*.1, foo.1 or something like that), but that's probably
> wishful thinking!
>
> Cheers,
>
> Ken
>
>
>
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Adrian Klaver
adrian(dot)klaver(at)aklaver(dot)com