Returns the sum of a set of values contained in a specified field on a query.
Sum( expr )
The expr placeholder represents a string expression identifying the field that contains the numeric data you want to add or an expression that performs a calculation using the data in that field. Operands in expr can include the name of a table field, a constant, or a function (which can be either intrinsic or user-defined but not one of the other SQL aggregate functions).
The Sum function totals the values in a field. For example, you could use the Sum function to determine the total cost of freight charges.
The Sum function ignores records that contain Null fields. The following example shows how you can calculate the sum of the products of UnitPrice and Quantity fields:
SELECT Sum(UnitPrice * Quantity) AS [Total Revenue]
FROM [Order Details];
You can use the Sum function in a query expression. You can also use this expression in the SQL property of a QueryDef object or when creating a Recordset based on an SQL query.