![SUBSTRING function [String]](arrow-left.gif){kind=icon}
![SUSER_ID function [System]](arrow-right.gif){kind=icon}
Returns the total of the specified expression for each group of rows.
SUM ( expression | DISTINCT column-name )
expression The object to be summed. This is commonly a column name.
DISTINCT column-name Computes the sum of the unique values in column-name for each group of rows. This is of limited usefulness, but is included for completeness.
The following statement returns the value 3749146.740:
SELECT SUM( salary ) FROM Employees
Rows where the specified expression is NULL are not included.
Returns NULL for a group containing no rows.
Chapter 2, “Using OLAP” in the System Administration Guide: Volume 2
