Re: Accumulated sums in SQL query

I think,that is not good solution. What will happen when some records
have the same date? I suggest to operate on rowid or something like
thaţ (maybe some serial?) and everything will be good.
But, when each row has different date, its good :)
regards.
marek

On Mon, Oct 28, 2002 at 03:55:46PM +0100, Kabai J?zsef (I don't know why;) wrote:
: Thank you Christoph this logic helped me a lot.
: Regards Joseph
: ----- Original Message -----
: From: "Christoph Haller" <ch(at)rodos(dot)fzk(dot)de>
: To: <kabai(at)audiobox(dot)hu>
: Cc: <pgsql-sql(at)postgresql(dot)org>
: Sent: Monday, October 28, 2002 1:27 PM
: Subject: Re: [SQL] Accumulated sums in SQL query
:
:
: > >
: > > OK I have a table named bank_account_movements containing two columns
: > =
: > > date and amount:
: > >
: > > date amount (in USD)
: > > -------------------------------------
: > > 2002-10-01 20
: > > 2002-10-02 30
: > > 2002-10-03 -15
: > > 2002-10-04 -5
: > > 2002-10-05 -3
: > > 2002-10-06 10
: > >
: > > my goal is to create a view from it adding an extra column named =
: > > balance!
: > >
: > > date amount (in USD) balance
: > > -----------------------------------------------------------
: > > 2002-10-01 20 20
: > > 2002-10-02 30 50
: > > 2002-10-03 -15 35
: > > 2002-10-04 -5 30
: > > 2002-10-05 -3 27
: > > 2002-10-06 10 17
: > >
: > > The balance is 0+20=20, 0+20+30=50, 0+20+30-15=35 and so on...
: > > how would you write the SQL query?
: > >
: >
: > My first approach is write a small plpgsql function
: > (based on the table definition below) like
: >
: > CREATE TABLE amountlist (date TIMESTAMP,amount INTEGER);
: > INSERT INTO amountlist VALUES ('2002-10-01 00:00:00', 20 ) ;
: > INSERT INTO amountlist VALUES ('2002-10-02 00:00:00', 30 ) ;
: > INSERT INTO amountlist VALUES ('2002-10-03 00:00:00',-15 ) ;
: > INSERT INTO amountlist VALUES ('2002-10-04 00:00:00', -5 ) ;
: > INSERT INTO amountlist VALUES ('2002-10-05 00:00:00', -3 ) ;
: > INSERT INTO amountlist VALUES ('2002-10-06 00:00:00', 10 ) ;
: > CREATE FUNCTION calc_balance(TIMESTAMP) RETURNS INTEGER AS '
: > DECLARE balance INTEGER;
: > BEGIN
: > SELECT INTO balance SUM(amount) FROM amountlist WHERE date <= $1 ;
: > RETURN balance;
: > END;
: > ' LANGUAGE 'plpgsql' ;
: >
: > SELECT date,amount,calc_balance(date) FROM amountlist;
: > date | amount | calc_balance
: > ------------------------+--------+--------------
: > 2002-10-01 00:00:00+02 | 20 | 20
: > 2002-10-02 00:00:00+02 | 30 | 50
: > 2002-10-03 00:00:00+02 | -15 | 35
: > 2002-10-04 00:00:00+02 | -5 | 30
: > 2002-10-05 00:00:00+02 | -3 | 27
: > 2002-10-06 00:00:00+02 | 10 | 37
: > (6 rows)
: >
: > Looks like what you are looking for, except the last value which
: > appears to be a typo.
: >
: > Regards, Christoph
: >
: >
: >
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:
:
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--
Marek Bartnikowski http://easy.eu.org
* It is more complicated than you think *