FIX: Attempting to Refresh Null TableDef Field Causes GP Fault

The information in this article applies to:

- Microsoft Visual Basic programming system for Windows, version 2.0

SYMPTOMS

A general protection (GP) fault occurs when you attempt to refresh a Null Fields collection of a TableDef. Instead, you should receive this error: "Method not applicable to this object."

When the Fields collection for a TableDef is not Null, the Refresh method works as expected.

STATUS

Microsoft has confirmed this to be a problem in Microsoft Visual Basic version 2.0 for Windows. This problem was corrected in Microsoft Visual Basic version 3.0 for Windows.

MORE INFORMATION

The following steps reproduce the problem:

1. Start the Professional Edition of VB.EXE with ODBC support already installed.

2. Add the following code to the Form_Click event procedure of Form1:

   Form_Click () Dim db As Database Dim tDef As TableDef DBName$ = "Server1"

      Set db = OpenDatabase(DBName$)   '* DBName$ name of Database
                                       '* that is already setup on
                                       '* the SQL Server. This
                                       '* DBName$ should be set to
                                       '* server name that listed in
                                       '* the ODBC.INI file.
      Set tDef = db.TableDefs(0)
   
      Set db = OpenDatabase(DBName$)
      tDef.Fields.Refresh      '* This should result in a
                               '* error, but instead results
                               '* in a GP Fault.
      End Sub
   
      In order to reproduce the problem, the first TableDef in the database,
      TableDefs(0), cannot have any fields associated with it.
   
   

3. Press the F5 key or ALT+R+S.

To avoid the problem, make sure the Fields collection is not Null before using the Refresh method. To do this, replace the tDef.Fields.Refresh statement in step 2 above with the following code:

   If Not tDef.Fields = Null Then
      tDef.Fields.Refresh
   End If