Returns the total of the specified expression for each group of rows.
SUM( expression | DISTINCT expression )
expression The object to be summed. This is commonly a column name.
DISTINCT expression Computes the sum of the unique values of expression in the input.
Rows where the specified expression is NULL are not included.
Returns NULL for a group containing no rows.
SQL/2003 Core feature. Syntax 2 is T611.
The following statement returns the value 3749146.740.
SELECT SUM( Salary ) FROM Employees;