There are applications where the running total for a series of
numbers needs to be calculated and displayed. While this might
be normally considered something that would be done with 3GL programming
techniques, it IS possible to calculate and query a running total
with SQL only.

First, we need to have a 'key' column to order the query by

Let's assume we have a table with a numeric column that we want.
We also need to have a column to order the display by, or a running
total does not make sense! Many times this will be a date column.
This could also be the PK of the table, or a single or multiple
column UK. I will use a date column in the following example.
Consider the table:

	SQL> desc Run_Total

 	Name                            Null?    Type
 	------------------------------- -------- ----
 	RUN_DATE                                 DATE
 	RUN_VALUE                                NUMBER

	SQL> select * from Run_Total;

	RUN_DATE  RUN_VALUE
	--------- ---------
	02-APR-97        10
	03-APR-97         5
	04-APR-97        20
	05-APR-97        15
	06-APR-97        45
	07-APR-97        12
	08-APR-97        37
	09-APR-97         9
	10-APR-97        23
	11-APR-97        19
	12-APR-97        10
	11 rows selected.

A self-join is needed to perform the correct sum.

In order to produce the running total, a self-join is needed to
sum all of the values of the table less than or equal to each
row.  The query is grouped by the records in the 'driving' table
in the join, and ordered by the run_date:<br>

	SELECT r1.run_date, r1.run_value, sum(r2.run_value) Running_Total
	  FROM Run_Total r1, Run_Total r2
	 WHERE r2.run_date <= r1.run_date
	 GROUP BY r1.run_date, r1.run_value
	 ORDER BY r1.run_date
	/

This query will produce the following output:

	RUN_DATE  RUN_VALUE RUNNING_TOTAL
	--------- --------- -------------
	02-APR-97        10            10
	03-APR-97         5            15
	04-APR-97        20            35
	05-APR-97        15            50
	06-APR-97        45            95
	07-APR-97        12           107
	08-APR-97        37           144
	09-APR-97         9           153
	10-APR-97        23           176
	11-APR-97        19           195
	12-APR-97        10           205
	
	11 rows selected.