Running Total

Keep a running total

schema:scott

DROP TABLE transact

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

If you want the money IN and money OUT to be separate a CASE expression can be used.

SELECT w AS dte, d AS description, 
CASE WHEN (a>=0) THEN a ELSE NULL END AS moneyIN,
CASE WHEN (a<0) THEN a ELSE NULL END AS moneyOUT,
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

In MySQL the following query also works:

SELECT whn, description, amount, @accumulator:=@accumulator+amount RunningTotal

FROM transact

In Oracle the following query works:

SELECT whn, amount, SUM(amount) OVER (ORDER BY whn)

FROM transact

SQL HACKS

Hack 10 Converting subqueries into joins

Hack 11 Converting aggregate subqueries into joins

Hack 14 Generate Combinations

Hack 16 Search for a String across columns

Hack 24 Multiply Across a Result Set

Hack 25 Keep a running total

Hack 25.5 Splitting and combining columns

Hack 26 Include the rows your JOIN forgot

Hack 30 Calculate the maximum/minimum of two fields

Hack 33 Get values and subtotals in one shot

Hack 50 Combine tables containing different data

Hack 51/52 Display rows as columns

Hack 55 Import Someone Else's Data

Hack 62 Issue Queries Without Using a Table

Hack 63 Generate rows without tables

Hack 70 Combine your queries

Hack 72 Extract a subset of the results

Hack 78 Break it down by Range

Hack 88 Test two values from a subquery

Hack 98 Find and stop long running queries

Hack 100 Run SQL from a Web Page