Re: complicated running aggregate

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От Greg Smith
Тема Re: complicated running aggregate
Дата
Msg-id 4C236A59.1050504@2ndquadrant.com
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Ответ на complicated running aggregate  (Sim Zacks <sim@compulab.co.il>)
Ответы Re: complicated running aggregate  (Sim Zacks <sim@compulab.co.il>)
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Sim Zacks wrote:
> I am trying to build a query with a running total, but it is a bit
> complicated...Currently I'm generating this information using a plpsql loop, but I
> would like to change it to an SQL query, if possible.
>

It's hard to do a running total with the sort of requirements you have
using simple SQL.  If you have PostgreSQL 8.4, it's much much easier to
do that using the SQL Window functions:
http://www.postgresql.org/docs/current/static/tutorial-window.html

If you're on an earlier version, using a loop in a function is not a bad
approach.  Getting the query right without windowing is possible, but
painful enough that it may not be worth your trouble.

--
Greg Smith  2ndQuadrant US  Baltimore, MD
PostgreSQL Training, Services and Support
greg@2ndQuadrant.com   www.2ndQuadrant.us


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