ACC2000: How to Sum a Calculation in a Report

ID: Q208850

The information in this article applies to:

Microsoft Access 2000

Moderate: Requires basic macro, coding, and interoperability skills.

SUMMARY

This article demonstrates three methods that you can use to sum a calculated control in a report. Because the Sum() function, as well as the other aggregate (totals) functions can reference only a field and not a control, you must use one of these methods if you want to sum a calculated control.

MORE INFORMATION

If the expression in the calculated control does not include another aggregate function, you can sum the expression by repeating it in the report or group footer section and taking its sum. If the expression does include another aggregate function, repeating the expression does not work because Microsoft Access cannot sum a sum. Instead, use a running sum or a function to hold the results.

To demonstrate the three methods, this article uses a report based on the Order Details table in the sample database Northwind.mdb.

NOTE: For calculating totals in a page footer section, use only methods two and three.

Creating the Report

To create the report, follow these steps:

Open the sample database Northwind.mdb.

Create a report based on the Order Details table in Design View.

Create an OrderID group by clicking Sorting And Grouping on the View menu, and then entering the following information in the Sorting And Grouping dialog box:


   Field/Expression: OrderID
   Group Header: Yes
   Group Footer: Yes

Add a report header and footer section to the report by clicking Report Header/Footer on the View menu.

Method 1: Summing Expressions That Do Not Contain Aggregate Functions

To sum a calculation that does not contain an aggregate function, repeat the calculation with the Sum() function. To use this method, follow these steps:

Add a text box control to the report's detail section to calculate the product of two fields. Set the control's properties as follows:


   Name: Extended Price
   ControlSource: =[UnitPrice] * [Quantity]

Add a text box control in the OrderID group footer section to calculate the total for the group. Set the following properties for the control:


   Name: Order Total
   ControlSource: =Sum([UnitPrice] * [Quantity])

Add a text box control in the report's footer section to calculate the total for the report. Set the following properties for the control:


   Name: Report Total
   ControlSource: =Sum([UnitPrice] * [Quantity])

Preview the report to see the sum of the calculation.

Method 2: Summing Expressions That Contain Aggregate Functions

You can use a running sum to calculate totals for expressions that contain aggregate functions or that reference other controls. To use this method, follow these steps:

Add a text box control to the report's OrderID group footer section to calculate a control that charges freight only when the order is over $100. Set the following properties for the control.

NOTE: In the following example, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this example.


   Name: Freight
   ControlSource: =IIf(Sum([UnitPrice]*[Quantity])>100,0.05* _
                     Sum([UnitPrice]*[Quantity]),0)

Add a second text box control to the report's Order ID group footer section to calculate the running sum for this control. Set the following properties for the control.

NOTE: In the following example, an underscore (_) at the end of a line is used as a line-continuation character. Remove the underscore from the end of the line when re-creating this example.
```
   Name: FreightRunSum
   ControlSource: =IIf(Sum([UnitPrice]*[Quantity])>100,0.05* _
                  Sum([UnitPrice]*[Quantity]),0)
   RunningSum: Over Group
   Visible: No 
```
NOTE: When you test a running sum, set the Visible property to Yes to verify that the control is accumulating. Once you verify that it does, hide the control by setting the Visible property to No.

Add a text box control to the report's footer section to display the total by referencing the RunningSum property. Set the following properties for the control:


   Name: Freight Total
   ControlSource: =[FreightRunSum]

Preview the report to see the sum of the calculation.

Method 3: Summing Controls Calculated by Functions

If you use code to calculate a control, you must use a function to calculate its sum. You need the function to hold the results of the calculation across the records. To use this method, follow these steps:

Microsoft provides programming examples for illustration only, without warranty either expressed or implied, including, but not limited to, the implied warranties of merchantability and/or fitness for a particular purpose. This article assumes that you are familiar with the programming language being demonstrated and the tools used to create and debug procedures. Microsoft support professionals can help explain the functionality of a particular procedure, but they will not modify these examples to provide added functionality or construct procedures to meet your specific needs. If you have limited programming experience, you may want to contact a Microsoft Certified Solution Provider or the Microsoft fee-based consulting line at (800) 936-5200. For more information about Microsoft Certified Solution Providers, please see the following page on the World Wide Web:

http://www.microsoft.com/mcsp/

For more information about the support options available from Microsoft, please see the following page on the World Wide Web:

http://www.microsoft.com/support/supportnet/overview/overview.asp

Create a new module and enter the following code in the Declarations section:


Option Explicit
Dim OrderTotal As Double       ' Used for group total.
Dim GrandTotal As Double       ' Used for report total.

Add the following procedure to calculate the product of two fields:


Function CalcProduct (R as Report)
   Dim tmpAmount As Double
   tmpAmount = R![UnitPrice] * R![Quantity]
   ' Remember the total for the group.
   OrderTotal = OrderTotal + tmpAmount
   ' Remember the total for the report.
   GrandTotal = GrandTotal + tmpAmount
   CalcProduct = tmpAmount
End Function

Add the following procedure to initialize the report's variables to 0:


Function InitVars ()
   OrderTotal = 0
   GrandTotal = 0
End Function

Add the following procedure to retrieve the total for the group:


Function GetGroupTotal ()
   GetGroupTotal = OrderTotal
   ' Reset the variable to 0 for next group.
   OrderTotal = 0
End Function

Add the following procedure to retrieve the total for the report:


Function GetReportTotal ()
   GetReportTotal = GrandTotal
End Function

To initialize the variables to 0, set the report's OnOpen property as follows:
```
      OnOpen: =InitVars() 
```
and then add three text box controls to the report's detail section. Set the following properties for the text boxes:


   Text box 1:
      Name: UnitPrice
      ControlSource: UnitPrice

   Text box 2:
      Name: Quantity
      ControlSource: Quantity

   Text box 3:
      Name: TheProduct
      ControlSource: =CalcProduct([Report])

Add a text box control to the group footer section to display the total for the group. Set the following properties for the control:


   Name: GroupTotal
   ControlSource: =GetGroupTotal()

Add a text box control to the report's footer section to display the total for the report. Set the following properties for the control:


   Name: ReportTotal
   ControlSource: =GetReportTotal()

Preview the report to see the sum of the calculation.

REFERENCES

For more information about calculating totals in a report, click Microsoft Access Help on the Help menu, type "calculate a total or average for a group of or all records in a records in a report" in the Office Assistant or the Answer Wizard, and then click Search to view the topic.

Additional query words: inf


Keywords          : kbdta RptTotal 
Version           : WINDOWS:2000
Platform          : WINDOWS 
Issue type        : kbhowto

Last Reviewed: July 6, 1999