RUNNING_SUM: Calculating a Sum Over a Group of Rows

How to:

Calculate Running Sum Between the Current and a Prior Value of a Field

Given an aggregated input field and an offset, RUNNING_SUM calculates the sum of the values between the current row of the report output and one or more prior rows, within a sort break or the entire table. The reset point for the calculation is determined by the sort field specified, the entire table, or the value of the PARTITION_ON parameter described in Specify the Partition Size for Simplified Statistical Functions.

Syntax: How to Calculate Running Sum Between the Current and a Prior Value of a Field

RUNNING_SUM(field, reset_key, lower)

where:

field

Numeric

The field to be used in the calculation.

reset_key

Identifies the point at which the running sum restarts. Valid values are:

The name of a sort field in the request.
PRESET, which uses the value of the PARTITION_ON parameter, as described in Specify the Partition Size for Simplified Statistical Functions.
TABLE, which indicates that there is no break on a sort field.

Note: The values used in the calculations depend on the sort sequence (ascending or descending) specified in the request. Be aware that displaying a date or time dimension in descending order may produce different results than those you may expect.

lower

Is the starting point in the partition for the running sum. Valid values are:

A negative number, which identifies the offset from the current row.
B, which specifies the beginning of the sort group.

Example: Calculating a Running Sum

The following request calculates a running sum of the current value and previous value of QUANTITY_SOLD within the reset point set by the PARTITION_ON parameter, which is the sort field PRODUCT_CATEGORY.

SET PARTITION_ON=PENULTIMATE
TABLE FILE wflite
SUM QUANTITY_SOLD
COMPUTE RSUM = RUNNING_SUM(QUANTITY_SOLD,PRESET,-1);
BY PRODUCT_CATEGORY
BY PRODUCT_SUBCATEG
ON TABLE SET PAGE NOLEAD
ON TABLE SET STYLE *
GRID=OFF,$
ENDSTYLE
END

The output is shown in the following image. The first value for RSUM is the value in the Accessories category for Quantity Sold, as there is no prior value. The second value for RSUM is the sum of the values for Headphones and Charger, the third is the sum of the values for Headphones and Universal Remote Controls. Then, the calculations start over for Camcorder, which is the reset point.