Re: summing tables

----- Original Message -----
From: "Tom Lane" <tgl@sss.pgh.pa.us>
To: "Viorel Dragomir" <bigchief@vio.ro>
Cc: <pgsql-sql@postgresql.org>
Sent: Tuesday, July 15, 2003 6:42 PM
Subject: Re: [SQL] summing tables


> "Viorel Dragomir" <bigchief@vio.ro> writes:
> > Indeed it was a mistake not to put the table_name. in where clause.
> > But this doesn't resolve the problem.
>
> > Do you know in which order the update will modify the rows?
>
> No, and *it does not matter*.  You are forgetting that this all runs
> under MVCC rules.  The sub-SELECTs will see the pre-existing versions
> of the rows, whether or not the UPDATE has yet produced new versions.

Yes that was correct.
I forgot that the subselect sees only the old rows.

And the ORDER option will not make any difference, only making fool out of
myself. :)
I don't know if the problem is solved with my posted function.

Anyway this is the mail that started all [i get a lot of emails and i'm not
really searching for a solution on this matter]:
"
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
"