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
>
> ---------------------------(end of broadcast)---------------------------
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