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Performs an aggregate computation that the UltraLite runtime does not provide.
SUM( expression )
An aggregate expression calculates a single value from a range of rows.
An aggregate expression is one in which either an aggregate function is used, or in which one or more of the operands is an aggregate expression.
When a SELECT statement does not have a GROUP BY clause, the expressions in the select-list must be either all aggregate expressions or none of the expressions can be an aggregate expression. When a SELECT statement does have a GROUP BY clause, any non-aggregate expression in the select-list must appear in the GROUP BY list.
For example, the following query computes the total payroll for employees in the employee table. In this query, SUM( salary ) is an aggregate expression:
SELECT SUM( salary ) FROM employee