Is it possible...

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От Uwe C. Schroeder
Тема Is it possible...
Дата
Msg-id 200408240847.43584.uwe@oss4u.com
обсуждение исходный текст
Ответы Re: Is it possible...  (Joe Conway <mail@joeconway.com>)
Re: Is it possible...  (Richard Huxton <dev@archonet.com>)
Список pgsql-general
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Hi all,

I wasn't able to get a usable answer by googling: Is there a way to create a
view on a table that converts rows to columns ?
Example:
I have a table

create table blah (
    id int4 serial,
    parentid int4,
    pname varchar(64),
    pvalue varchar(128)
);

which is basically a classic key/value pair. Parentid is a field defining that
certain rows belong to the same entity, i.e.:

1  1  'firstkey' 'firstvalue'
2  1  'secondkey' 'secondvalue'
...
...
10 2 'firstkey' 'firstvalue'
...

All the "parents" have the same set of keys - guaranteed.
I'd need to convert this into a table which has the  keynames as columns and
one row per "parentid", i.e.:

parentid firstkey     secondkey
1            firstvalue  secondvalue
2            firstvalue  secondvalue


I hate the idea of writing code that really creates and fills a table,
particularly since the original table has a lot of rows.

Is the above doable with a view?
Any pointers will be appreciated.

Thanks

    UC

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