From: | Ryan Murphy <ryanfmurphy(at)gmail(dot)com> |
---|---|
To: | Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> |
Cc: | "pgsql-general(at)postgresql(dot)org" <pgsql-general(at)postgresql(dot)org> |
Subject: | Re: postgres question: Views with duplicate field names |
Date: | 2016-09-05 20:13:21 |
Message-ID: | CAHeEsBfLfD+eE20T8APy8DSJGXyYchsFqSQP+UrGtW477M9Nnw@mail.gmail.com |
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Lists: | pgsql-general |
Interesting, thanks! Do you know why the first one fails instead of doing
that renaming process, while your version succeeds?
On Monday, September 5, 2016, Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com>
wrote:
> On 09/05/2016 12:55 PM, Ryan Murphy wrote:
>
>> Hello, I have a question about views in Postgres.
>>
>> Given a table like so:
>>
>> create table todo (
>> id serial,
>> task text,
>> done_time timestamp default null
>> );
>>
>> it is legal (though perhaps not advised, by some) to query it like so:
>>
>> select task, * from todo;
>>
>> This gives a result with 2 redundant "task" fields (with duplicate names):
>>
>> task | id | task | done_time
>> --------------+----+--------------+-----------
>> wash the dog | 1 | wash the dog |
>>
>> However, if I try to make a view of this I hit a problem: views can't
>> have duplicate field names:
>>
>> create view task2 as select task, * from todo;
>>
>> ERROR: column "task" specified more than once
>>
>> I understand this may seem like a silly thing to want to do, but my
>> question is if there is an easy way to automatically de-dup the columns
>> of the query so I can create a view from it. Or is there any
>> fundamental reason why views can't be allowed to have duplicate columns,
>> just like the result set above?
>>
>
> test=> create view task2 as select task AS task_1 , * from todo;
> CREATE VIEW
>
> test=> \d task2
> View "public.task2"
>
> Column | Type | Modifiers
>
> -----------+-----------------------------+-----------
>
> task_1 | text |
>
> id | integer |
> task | text |
> done_time | timestamp without time zone |
>
>
>
>> Thanks!
>>
>> Ryan
>>
>
>
> --
> Adrian Klaver
> adrian(dot)klaver(at)aklaver(dot)com
>
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