From: Dias Costa <dcosta@lnec.pt>
To: George Handin <postgresql@dafunks.com>
Cc: Richard Broersma Jr <rabroersma@yahoo.com>
Cc: pgsql-sql@postgresql.org
Subject: Re: Query to return modified results at runtime?
Date: Thu, 08 Jun 2006 17:32:45 +0100
Message-ID: <4488512D.209@lnec.pt> (raw)
In-Reply-To: <44884752.7030303@dafunks.com>
References: <20060608043236.96435.qmail@web31810.mail.mud.yahoo.com>
<44884752.7030303@dafunks.com>
Hi,
You can use the construct *Case When* but You have to have
Your information structured (even if only in Your mind)
in order to achive the results You want.
So, suposse You have for the color Blue the letter A,
for the color Red the letter D, for the color Green the
letter B and finally for the color Orange the letter C.
For the following data:
create table dcosta.colors
(id numeric(3),
Color varchar(12));
insert into dcosta.colors values(1, 'Blue');
insert into dcosta.colors values(2, 'Red');
insert into dcosta.colors values(3, 'Green');
insert into dcosta.colors values(4, 'Orange');
You can use the following instruction:
*
*SELECT ID, Color,
CASE WHEN color = 'Blue' THEN 'A'
WHEN color = 'Red' THEN 'D'
WHEN color = 'Green' THEN 'B'
WHEN color = 'Orange' THEN 'C'
ELSE 'other'
END
FROM dcosta.colors;
Obviously You can ommit the column Color from the select clause.
Hope I helped
Dias Costa
George Handin wrote:
> Richard Broersma Jr wrote:
>
>>> ID Color
>>> --- -------
>>> 1 Blue
>>> 2 Red
>>> 3 Green
>>> 4 Orange
>>>
>>> How would I rewrite the query to return results where the colors are
>>> replaced by letters to give the following results?
>>>
>>> ID Color
>>> --- -------
>>> 1 A
>>> 2 D
>>> 3 B
>>> 4 C
>>
>>
>>
>> http://www.postgresql.org/docs/8.1/interactive/functions-conditional.html
>>
>>
>> this is probably the easiest to implement but hard to mangage over
>> time. Another solution would
>> be to create color_code table that is referenced by your test table.
>> Then when you can create a
>> query as: select a.ID, b.code from test as a join color_code as b on
>> a.color = b.color;
>>
>> There are additional solutions to this also. But these two are
>> probably the easiest.
>
>
> Thanks!
>
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>
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To: pgsql-sql@postgresql.org
Cc: dcosta@lnec.pt, postgresql@dafunks.com, rabroersma@yahoo.com
Subject: Re: Query to return modified results at runtime?
In-Reply-To: <4488512D.209@lnec.pt>
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