Re: summing tables

update table_name
set c = a + b + (select c from table_name as x where x.seq = seq-1)
where c is null;

additional checks are required if you want to update c when c is not null
if all the c are null then this query will do nothing

god help u
:)

----- Original Message ----- 
From: "Erik Thiele" <erik@thiele-hydraulik.de>
To: <pgsql-sql@postgresql.org>
Sent: Tuesday, July 15, 2003 3:09 PM
Subject: [SQL] summing tables


> 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
> 
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