Q166929: FIX: DBCombo Control Change Event Does Not Fire

Article: Q166929
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:5.0
Operating System(s): 
Keyword(s): kbVBp kbVBp500 kbControl
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition for Windows, version 5.0 
- Microsoft Visual Basic Enterprise Edition for Windows, version 5.0 
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SYMPTOMS
========

Program code in the Change event procedure of Microsoft Visual Basic will not
execute. Applications written using Visual Basic version 4.0 may no longer work
as expected if functionality is based on responding to a Change event in a
DBCombo control.

RESOLUTION
==========

To correct this problem, use one of the following methods.

- Install Visual Studio 97 Service Pack 2 or later.

-or-

- To resolve this problem without installing Visual Studio 97 Service Pack 2 or
  later:

  Replace the functional code of the Change event procedure with equivalent code
  entered in the Click event procedure. This code is conditioned by testing the
  DataChanged property of the DBCombo control.

An example of this workaround is as follows:

     Private Sub DBCombo1_Click(Area As Integer)
        If DBCombo1.DataChanged Then
           ' Any code that would normally be in the Change Event
           ' or call the Change event like this: DBCombo1_Change
           ' followed by code that resets the DataChanged property, such as:
           DBCombo1.DataChanged = False
        End IF
     End Sub

If the user normally tabs to the DBCombo control and then uses arrow keys to
navigate to an item in the list, similar code would be required in the KeyPress,
KeyDown and/or KeyUp event procedures. In this case, it would be more effective
to write a single form-level module to replace the code of the DBCombo Change
event and call it from the various places where the DBCombo.DataChanged property
would be tested.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. This bug has been fixed in Visual Studio 97 Service
Pack 2.

For more information, please see the following article in the Microsoft Knowledge
Base:

Q170365 INFO: Visual Studio 97 Service Packs - What, Where, and Why

MORE INFORMATION
================

Steps to Reproduce Behavior
---------------------------

1. Start a new Standard EXE project. Form1 is created by default.

2. On Form1, place two Data Controls named Data1 and Data2.

3. Set the following values for the properties of Data1:

  Name            Data1
  DatabaseName    C:\Program Files\DevStudio\VB\Biblio.mdb (or the
                  appropriate path to that database)
  RecordsetType   0 - Table
  RecordSource    Titles

4. Set the following values for the properties of Data2:

  Name            Data2
  DatabaseName    C:\Program Files\DevStudio\VB\Biblio.mdb (or the
                  appropriate path to that database)
  RecordsetType   2 - Snapshot
  RecordSource    SELECT PubID, Name FROM Publishers ORDER BY Name

5. Place a DBCombo control on the form.

6. Set the following values for the properties of DBCombo1:

  Name            DBCombo1
  BoundColumn     PubID
  DataField       PubID
  DataSource      Data1
  ListField       Name
  RowSource       Data2
  Style           0 [ASCII 150] dbcDropDownCombo

7. In the module for the form, enter the following:

        Private Sub DBCombo1_Change()
           Debug.Print "In the Change Event Method"
        End Sub

8. Run the form. Click the down arrow to the DBCombo to open the list portion.

9. Click any line in the list portion. Observe the Immediate (Debug) Window.

Additional query words:

======================================================================
Keywords          : kbVBp kbVBp500 kbControl 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVBA500 kbVB500
Version           : WINDOWS:5.0
Issue type        : kbbug
Solution Type     : kbfix

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