ACC2000: How to Use DSum to Create a Running Sum on a Form

Reports have a RunningSum property; forms do not. This article shows you how to create a running sum on a form.

NOTE: This article explains a technique demonstrated in the sample file, FrmSmp00.mdb. For information about how to obtain this sample file, please see the following article in the Microsoft Knowledge Base:

To create a running sum on a form, the underlying table or query must have a unique, sequential, ID field, such as an AutoNumber or a Date/Time timestamp field. If your table does not have such a field, you can open the table in Design view and add a new field to create one.

NOTE: The following example uses the DSum() function to generate a running sum on a form. For additional information about how to obtain this sample file, please see the following article in the Microsoft Knowledge Base:
The following example uses the sample database Northwind.mdb to show you how to create a text box on a form that sums the freight amount for the current customer order and all preceding customer orders:

1. Start Microsoft Access and open the sample database Northwind.mdb.
2. Create the following new form based on the Orders table.
   
   NOTE: To improve readability, the underscore (_) is used in the following example as a line-continuation character. Remove the underscore from the end of the line when you are re-creating this example.
   

         Form:  Form1
         --------------------
         RecordSource: Orders
   
         Text Box: Order ID
            ControlSource: OrderID
         Text Box: Total
            ControlSource: =DSum("[Freight]","Orders",_
                                 "[OrderID] <= Forms![Form1]![OrderID]")
   
   						

   The DSum() function calculates the sum of all freight charges on orders with an Order number less than or equal to the currently displayed order number. For this reason, it is important to have a unique and sequential ID field.
3. View the form in Form view. Note that the Total text box accumulates total freight charges for each order as you move from record to record.