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.
Dim curX As Currency
curX = DSum("[Freight]", "Orders", "[ShipCountry] = 'UK'")
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.
Dim curX As Currency
curX = DSum("[Freight]", "Orders", _
"[ShipCountry] = 'UK' AND [ShippedDate] > #1-1-95#")
You can use a domain function in the Update To row of an update query. For example, suppose you want to track current sales by product in a Products table. You could add a new field called SalesSoFar to the Products table, and run an update query to calculate the correct values and update the records. Create a new query based on the Products table, and click Update on the Query menu. Add the SalesSoFar field to the query grid, and enter the following in the Update To row:
DSum("[Quantity]*[UnitPrice]", "Order Details", "[ProductID] = " _
& [ProductID])
When the query is run, Microsoft Access calculates the total amount of sales for each product, based on information from an Order Details table. The sum of sales for each product is added to the Products table.