From: Jean-Luc Lachance <jllachan@nsd.ca>
To: Erik Thiele <erik@thiele-hydraulik.de>
Cc: pgsql-sql@postgresql.org
Subject: Re: summing tables
Date: Tue, 15 Jul 2003 11:02:17 -0400
Message-ID: <3F141779.204E02CD@nsd.ca> (raw)
References: <20030715140921.7c5a6a6c.erik@thiele-hydraulik.de>
Erik,
If you intent is to get a running total of a and b ordered by seq, you
should try this (assuming the table name is t):
update t set c = ( select sum(a) + sum(b) from t t1 where t1.seq <=
t.seq);
You should have an index on seq.
If the table is very large, it is going to be painfully slow.
In that case you may want to think about using a function to step thru
each row.
JLL
Erik Thiele wrote:
>
> hi,
>
> i have a table consisting of 4 integers.
>
> seq is for making the table ordered. (ORDER BY SEQ ASC)
> a,b,c maybe null
>
> seq | a | b | c
> -----+----+----+---
> 0 | 1 | 2 | 3
> 1 | 1 | 2 |
> 2 | 5 | 7 |
> 3 | -2 | -4 |
>
> i am needing a sql statement to do
>
> c=a+b+"the c of the row with seq one less than myself"
>
> this statement has to run over the whole table, in seq order.
>
> how can this be acomplished???
>
> cu&thanks
> erik
>
> --
> Erik Thiele
>
> ---------------------------(end of broadcast)---------------------------
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To: pgsql-sql@postgresql.org
Cc: jllachan@nsd.ca, erik@thiele-hydraulik.de
Subject: Re: summing tables
In-Reply-To: <3F141779.204E02CD@nsd.ca>
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