|Access Developer Reference|
expression.DSum(Expr, Domain, Criteria)
expression A variable that represents an Application object.
|Expr||Required||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||Required||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.|
|Criteria||Optional||Variant||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.|
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.
|You can use either the DSum or Sum function in a calculated field expression in a totals query. If you use the DSum function, values are calculated before data is grouped. If you use the Sum function, the data is grouped before values in the field expression are evaluated.|
You may want to use the DSum function when you need to display the sum of a set of values from a field that is not in the record source for your form or report. For example, suppose you have a form that displays information about a particular product. You could use the DSum function to maintain a running total of sales of that product in a calculated control.
If you need to maintain a running total in a control on a report, you can use the RunningSum property of that control if the field on which it is based is included in the record source for the report. Use the DSum function to maintain a running sum on a form.
The following example totals the values from the Freight field for orders shipped to the United Kingdom. The domain is an Orders table. The criteria argument restricts the resulting set of records to those for which ShipCountry equals UK.
|Visual Basic for Applications|
The next example calculates a total by using two separate criteria. Note that single quotation marks (') and number signs (#) are included in the string expression, so that when the strings are concatenated, the string literal will be enclosed in single quotation marks, and the date will be enclosed in number signs.
|Visual Basic for Applications|