Microsoft KB Archive/121509

= ACC: Sample Function to Create a Running Sum on a Form =

Article ID: 121509

Article Last Modified on 1/19/2007

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APPLIES TO


 * Microsoft Access 2.0 Standard Edition
 * Microsoft Access 95 Standard Edition
 * Microsoft Access 97 Standard Edition

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This article was previously published under Q121509



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



SUMMARY
This article shows you how to create a sample user-defined function to compute a running sum on a form.

This article assumes that you are familiar with Visual Basic for Applications and with creating Microsoft Access applications using the programming tools provided with Microsoft Access. For more information about Visual Basic for Applications, please refer to your version of the "Building Applications with Microsoft Access" manual.

NOTE: Visual Basic for Applications is called Access Basic in Microsoft Access version 2.0. For more information about Access Basic, please refer to the "Building Applications" manual.



MORE INFORMATION
One way to compute a running sum on a form is to use the DSum function. For information about how to use the DSum function to compute a running sum on a form, please see the following article in the Microsoft Knowledge Base:

103183 ACC: How to Create a Running Sum on a Form

Using the method demonstrated in this article has the following advantages over using the DSum function:


 * The method demonstrated in this article does not require a sequential ID field. A required sequential ID field limits you to computing a running sum using a single ordering of your records.
 * Using the method demonstrated in this article is significantly faster than using the DSum function to compute a running sum.

How to Create and Use the RunSum Function
 Open the sample database Northwind.mdb (or NWIND.MDB in version 2.0). Create a new module, and type the following line in the Declarations section if it is not already there:

Option Explicit

  Enter the following code in the module.

NOTE: In the following sample code, 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 code in Access Basic. Function RunSum (F As Form, KeyName As String, KeyValue, _       FieldToSum As String) '***********************************************************     ' FUNCTION: RunSum ' PURPOSE: Compute a running sum on a form. ' PARAMETERS: '   F        - The form containing the previous value to      '               retrieve. '   KeyName  - The name of the form's unique key field. '   KeyValue - The current record's key value. '   FieldToSum - The name of the field in the previous '                record containing the value to retrieve. ' RETURNS: A running sum of the field FieldToSum. ' EXAMPLE: =RunSum(Form,"ID",[ID],"Amount") '***********************************************************        Dim RS As Recordset Dim Result

On Error GoTo Err_RunSum

' Get the form Recordset. Set RS = F.RecordsetClone

' Find the current record. Select Case RS.Fields(KeyName).Type ' Find using numeric data type key value? Case DB_INTEGER, DB_LONG, DB_CURRENCY, _ DB_SINGLE, DB_DOUBLE, DB_BYTE RS.FindFirst "[" & KeyName & "] = " & KeyValue ' Find using date data type key value? Case DB_DATE RS.FindFirst "[" & KeyName & "] = #" & KeyValue & "#" ' Find using text data type key value? Case DB_TEXT RS.FindFirst "[" & KeyName & "] = '" & KeyValue & "'" Case Else MsgBox "ERROR: Invalid key field data type!" GoTo Bye_RunSum End Select

' Compute the running sum. Do Until RS.BOF Result = Result + RS(FieldToSum)

' Move to the previous record. RS.MovePrevious Loop

Bye_RunSum: RunSum = Result Exit Function

Err_RunSum: Resume Bye_RunSum

End Function   Create the following new query based on the Orders table and the Order Subtotals query. Save the query as qryOrders:      Query: qryOrders --     Type: select query Join: Orders.[OrderID] <-> [Order Subtotals].[OrderID]

NOTE: In version 2.0, there is a space in Order ID.

Field: OrderID Table: Orders Sort: Ascending Field: Subtotal Table: Order Subtotals  Use the Tabular Form Wizard to create a new form based on the qryOrders query. Include both fields on the form. Add a text box with the following properties to the new form:

Name: RunningSum

ControlSource: =RunSum([Form],"OrderID",[OrderID],"Subtotal")

Format: Currency

NOTE: In version 2.0, there is a space in the Order ID field. Save the form and then view it in Form view.</li> Select different records using the record selector. Note that the Runningsum field shows an accumulated total based on the Subtotal field.</li></ol>

Additional query words: total

Keywords: kbhowto kbprogramming kbusage KB121509

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