Running Total

In this example you are shown how to get a running total in a set of results.

Table 1 shows the results without the running total and Table 2 shows what we get with the running total.

Table 1
whn	description	amount
2006-11-01	Wages	50
2006-11-02	Company Store	-10
2006-11-03	Company Store	-10
2006-11-04	Company Store	-10
2006-11-05	Company Store	-10
2006-11-06	Company Store	-10

Table 2
whn	description	amount	balance
2006-11-01	Wages	50	50
2006-11-02	Company Store	-10	40
2006-11-03	Company Store	-10	30
2006-11-04	Company Store	-10	20
2006-11-05	Company Store	-10	10
2006-11-06	Company Store	-10	0

schema:scott

DROP TABLE transact

 CREATE TABLE transact(
  whn DATE,
  description VARCHAR(20),
  amount INTEGER );
INSERT INTO transact VALUES ('2006-11-01','Wages',50);
INSERT INTO transact VALUES ('2006-11-02','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-03','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-04','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-05','Company Store',-10);
INSERT INTO transact VALUES ('2006-11-06','Company Store',-10);

To calculate a running total a table needs to be joined to itself, each version can be called table x and table y.

SELECT x.whn, x.description, x.amount, 
       SUM(y.amount) AS balance
  FROM transact x
  JOIN transact y ON (x.whn>=y.whn)
  GROUP BY x.whn, x.description, x.amount

Learn how to split the amount table into cshIN and cshOUT

SELECT w AS dte, d AS description, a, balance
  FROM
  (SELECT x.whn AS w, x.description AS d, 
          x.amount AS a, SUM(y.amount) AS balance
     FROM transact x
     JOIN transact y ON (x.whn>=y.whn)
     GROUP BY x.whn, x.description, x.amount) t

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