ACC2000: How to Control Bound Form Transactions in Access Databases

• Microsoft Access 2000

SUMMARY

This article shows you how use Data Access Objects (DAO) to control transactions in a form that is based on a table (a bound form) in a Microsoft Access (Jet) database.

MORE INFORMATION

Typically, a developer needs to be able to let users of a database application commit all or none of their data changes on a form. In versions of Access earlier than version 2000, you could not encapsulate data changes made on bound forms within transactions. This was because all transactions in bound forms were handled in a separate workspace, accessible only to Microsoft Access.

In Microsoft Access 2000, however, you can use a combination of Data Access Objects (DAO) and the new, form Recordset property to provide this capability. The example in this article assumes that the user wants to be prompted to commit all changes made to the form's data when the user closes the form. At that time, the user can either commit all of the changes or none of the changes.

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:

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Controlling Transactions on Bound Forms

1. Open the sample database Northwind.mdb.



2. Create a new form based on the Customers table.



3. Add all fields to the detail section of the form.



4. On the View menu, click Code to view the module of the form, and then add the following code to the module:




Option Compare Database
Option Explicit

Private boolFrmDirty As Boolean
Private boolFrmSaved As Boolean

Private Sub Form_AfterDelConfirm(Status As Integer)
    If Me.Saved = False Then Me.Saved = (Status = acDeleteOK)
End Sub

Private Sub Form_AfterUpdate()
    Me.Saved = True
End Sub

Private Sub Form_Delete(Cancel As Integer)
    If Me.Dirtied = False Then DBEngine.BeginTrans
    Me.Dirtied = True
End Sub

Private Sub Form_Dirty(Cancel As Integer)
    If Me.Dirtied = False Then DBEngine.BeginTrans
    Me.Dirtied = True
End Sub

Private Sub Form_Open(Cancel As Integer)
    Dim db As DAO.Database
    Dim rs As DAO.Recordset
    Set db = CurrentDb
    Set rs = db.OpenRecordset("SELECT * FROM Customers", dbOpenDynaset)
    Set Me.Recordset = rs
End Sub

Private Sub Form_Unload(Cancel As Integer)
    Dim msg As Integer
    If Me.Saved Then
        msg = MsgBox("Do you want to commit all changes?", vbYesNoCancel)
        Select Case msg
            Case vbYes
                DBEngine.CommitTrans
            Case vbNo
                DBEngine.Rollback
            Case vbCancel
                Cancel = True
        End Select
    Else
        If Me.Dirtied Then DBEngine.Rollback
    End If
End Sub

Public Property Get Dirtied() As Boolean
    Dirtied = boolFrmDirty
End Property

Public Property Let Dirtied(boolFrmDirtyIn As Boolean)
    boolFrmDirty = boolFrmDirtyIn
End Property

Public Property Get Saved() As Boolean
    Saved = boolFrmSaved
End Property

Public Property Let Saved(boolFrmSavedIn As Boolean)
    boolFrmSaved = boolFrmSavedIn
End Property 

5. On the Debug menu, click Compile Northwind.



6. On the File menu, click Save Northwind.



7. When you are prompted, save the form as frmCustomers.



8. Open the frmCustomers form in Form view. Note that the form is populated with data.



9. Make some changes by editing an existing record, by inserting some new records, and by deleting some records.



10. Close the form. Note that you are prompted if you want to commit all changes.



11. Click No.



12. Open the form in Form view. Note that none of the changes that you made in step 9 were saved to the database.



13. Repeat steps 9 and 10.



14. When you are prompted to commit all changes, click Yes.



15. Open the form in Form view. Note that all the changes that you made were saved to the database.

REFERENCES

For additional information about controlling bound form transactions in an Access project (ADP) file, click the article number below to view the article in the Microsoft Knowledge Base:

Q200880 ACC2000: Controlling Bound Form Transactions in Access Projects

Additional query words: inf

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