Q175691: BUG: VFP CDX with EMPTY Function Is Not Recognized in VB

Article: Q175691
Product(s): Microsoft Visual Basic for Windows
Version(s): WINDOWS:5.0,6.0
Operating System(s): 
Keyword(s): kbVBp500 kbVBp600 kbGrpDSVBDB
Last Modified: 11-JAN-2001

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The information in this article applies to:

- Microsoft Visual Basic Professional Edition for Windows, versions 5.0, 6.0 
- Microsoft Visual Basic Enterprise Edition for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

FoxPro indexes that contain the function EMPTY or ISBLANK will not be recognized
in Visual Basic. Indexes with this function are recognized by Visual Basic 4.0.
The following error will be generated under NT and Windows 2000:

  An application error has occurred
  and an application error log is being generated.

  VB5.exe
  Exception Access Violation (0xc0000005),Address .........

Visual Basic is terminated by this error.

In Windows 95 and Windows 98, no error is returned because the index is not seen.

RESOLUTION
==========

Compare field to " " instead of using EMPTY. The same results are achieved.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article. We are researching this bug and will post new
information here in the Microsoft Knowledge Base as it becomes available.

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

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

1. Create a Visual Basic project and choose DAO 3.5 under project references.

2. In FoxPro 2.5, use the customer table and set up some indexes on cno, state
  and ono. The CDX file with the same name as the table file will contain the
  indexes.

3. Place 2 CommandButtons on the form, and paste in the following code:

        Option Explicit

        Dim FoxDataDB As Database
        Dim RS As Recordset
        Dim myidx As Index

        Private Sub Command1_Click()
          RS.Close
          FoxDataDB.Close
          Set RS = Nothing
          Set FoxDataDB = Nothing
          Unload Me
        End Sub

        Private Sub Command2_Click()
           For Each myidx In FoxDataDB.TableDefs("customer").Indexes
              Debug.Print myidx.Name
              RS.Index = myidx.Name
           Next
        End Sub

        Private Sub Form_Load()

        Set FoxDataDB = Workspaces(0).OpenDatabase( _
                           "d:\fpw26\tutorial", _
                           False, False, "FoxPro 2.5;")
           Set RS = FoxDataDB.OpenRecordset("customer", dbOpenTable)

        End Sub

4. Run the code above and note that the index names are printed.

5. Delete some phone numbers from the database above and add the following index
  by choosing Database Setup from the menu in FoxPro:

  IIF(EMPTY(phone), state, phone)

6. Run the code above and note that you get the error above under NT and Windows
  2000. Under Windows 95 and Windows 98, the index will not be recognized.

7. Remove the phone index, and the program will run successfully if the index
  has not become corrupted.

Additional query words: Dr. Watson function complex immediate inline kbVBp500bug kbVBp kbWinOS98 kbDSupport kbdse kbVBp600 kbDAO350 kbVFP250

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Keywords          : kbVBp500 kbVBp600 kbGrpDSVBDB 
Technology        : kbVBSearch kbAudDeveloper kbZNotKeyword6 kbZNotKeyword2 kbVB500Search kbVB600Search kbVBA500 kbVBA600 kbVB500 kbVB600
Version           : WINDOWS:5.0,6.0
Hardware          : x86
Issue type        : kbbug

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