From: Greg Stark <gsstark@mit.edu>
To: Viorel Dragomir <bc@vio.ro>
Cc: Greg Stark <gsstark@mit.edu>
Cc: pgsql-sql@postgresql.org
Subject: Re: summing tables
Date: 15 Jul 2003 11:38:21 -0400
Message-ID: <87u19nls0i.fsf@stark.dyndns.tv> (raw)
In-Reply-To: <010201c34ae2$b35b3830$0600a8c0@fix.ro>
References: <20030715140921.7c5a6a6c.erik@thiele-hydraulik.de>
<001501c34aca$e70ca280$0600a8c0@fix.ro>
<20030715143925.54716ed4.erik@thiele-hydraulik.de>
<007101c34ad6$3e0249e0$0600a8c0@fix.ro>
<878yqzn8k5.fsf@stark.dyndns.tv>
<010201c34ae2$b35b3830$0600a8c0@fix.ro>
"Viorel Dragomir" <bc@vio.ro> writes:
> Anyway, in real life this update modifies only one row with a value wich is
> diff of null. It was really handy if it was specified the option ORDER for
> the update command.
Are you hoping to produce a running total? That's very difficult in standard
SQL. That would be very different from the query you asked for.
Running totals, ranking, lead/lag, are all things that are very difficult to
do in standard SQL. They don't fit in the unordered set model that SQL follows
so doing them without special non-standard functions is very hard and
inefficient.
The functions to do them don't fit well within the SQL universe either, which
might be why they don't exist yet in postgres.
--
greg
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To: pgsql-sql@postgresql.org
Cc: gsstark@mit.edu, bc@vio.ro
Subject: Re: summing tables
In-Reply-To: <87u19nls0i.fsf@stark.dyndns.tv>
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