RE: running totals

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От Joel Burton
Тема RE: running totals
Дата
Msg-id 3A2E7AFE.1129.702A05B@localhost
обсуждение исходный текст
Ответ на Re: running totals  ("Joel Burton" <jburton@scw.org>)
Ответы Re: running totals  (Tom Lane <tgl@sss.pgh.pa.us>)
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> >CREATE VIEW tape_view AS
> >SELECT id, tape_name, sum(runtime)
> >FROM tape t,
> >show s
> >WHERE t.id = s.tape_id
> >GROUP BY id, tape_name;
> >
> >Which means you can just
 >
> >SELECT * FROM tape_view;
>
> Wow! This is a great idea... I had never thought of using a view
for
> this type of calculation.  I always did it the hard way.  Question
> though, does the VIEW keep the sum current at all times, or does
it
> just update when a query is run on the VIEW?


The view *IS* a query, really. When you SELECT from the VIEW,
you're really running a SELECT. So, no, merely updating in the the
table doesn't affect the view, only when you select from the view.



--
Joel Burton, Director of Information Systems -*- jburton@scw.org
Support Center of Washington (www.scw.org)

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