Application.DSum (Access)
You can use the DSum function to calculate the sum of a set of values in a specified set of records (a domain).
For example, you could use the DSum function in a calculated field expression in a query to calculate the total sales made by a particular employee over a period of time. Or you could use the DSum function in a calculated control to display a running sum of sales for a particular product. If no record satisfies the criteria argument, or if domain contains no records, the DSum function returns a Null. Whether you use the DSum function in a macro, module, query expression, or calculated control, you must construct the criteria argument carefully to ensure that it will be evaluated correctly. You can use the DSum function to specify criteria in the Criteria row of a query, in a calculated field in a query expression, or in the Update To row of an update query.
Dim curX As Currency
curX = DSum("[Freight]", "Orders", "[ShipCountry] = 'UK'")
Arguments
The following arguments are required:
Expr (String) - An expression that identifies the numeric field whose values you want to total. It can be a string expression identifying a field in a table or query, or it can be an expression that performs a calculation on data in that field. In expr, you can include the name of a field in a table, a control on a form, a constant, or a function. If expr includes a function, it can be either built-in or user-defined, but not another domain aggregate or SQL aggregate function.
Domain (String) - A string expression identifying the set of records that constitutes the domain. It can be a table name or a query name for a query that does not require a parameter.
Optional arguments
The following argument is optional
Criteria (String) - An optional string expression used to restrict the range of data on which the DSum function is performed. For example, criteria is often equivalent to the WHERE clause in an SQL expression, without the word WHERE. If criteria is omitted, the DSum function evaluates expr against the entire domain. Any field that is included in criteria must also be a field in domain; otherwise, the DSum function returns a Null.