Message-ID: <3F13F0EE.8040700@ecologic.de>
Date: Tue, 15 Jul 2003 14:17:50 +0200
From: Dani Oderbolz <oderbolz@ecologic.de>
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To: Erik Thiele <erik@thiele-hydraulik.de>, pgsql-sql@postgresql.org
Subject: Re: summing tables
References: <20030715140921.7c5a6a6c.erik@thiele-hydraulik.de>
In-Reply-To: <20030715140921.7c5a6a6c.erik@thiele-hydraulik.de>
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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
>
>
>  
>
Hi Erik,
this should do the trick:
(I have not yet considered the NULLS though...)
UPDATE table t set c = a + b + (Select c from table tt where tt.seq = 
t.seq -1)

Cheers, Dani