Re: Accumulated sums in SQL query

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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