Q169102: BUG: REQUERY() Problem with Private Datasessions Sharing a Table

Article: Q169102
Product(s): Microsoft FoxPro
Version(s): 5.0 5.0a
Operating System(s): 
Keyword(s): kbvfp
Last Modified: 10-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 5.0a 
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SYMPTOMS
========

In a multi-user application, if you have two forms with private DataSessions
that include cursors that are based on the same table, the REQUERY() function
returns old data on a form opened after the update of data on another session of
the application.

CAUSE
=====

The problem is in the buffering of data, and the fact that REQUERY() is not
overriding the SET REFRESH timing. If the form is creating a second DataSession
with a cursor pointing to the same table as the first DataSession, the new
DataSession uses the data from the existing cursor.


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
---------------------------

NOTE: This is a multi-user test. References to User1 and User2 indicate two
separate instances of Visual FoxPro. This can be on separate machines, or two
sessions of Visual FoxPro on the same machine.

In a project with at least one table ('Table1' in this example), create the
following:

1. Two local views based on Table1.

2. Filter the views to return one record. Ensure it is the same record in both
  views.

3. Create two forms: Form1 and Form2.

4. Place one view in the DataEnvironment of Form1.

5. Place the second view in the DataEnvironment of Form2.

6. Place two or three text boxes on each form bound to fields in the respective
  views

7. Set the DATASESSION property to Private on both forms.

8. Set the BUFFERMODE of each form to anything but None.

9. On Form1, create a command button with the following code:

        TABLEUPDATE()
        FLUSH

10. Create a second command button on Form1 with the following code:

        DO FORM FORM2

11. Create a command button on Form2 with the following code:

        REQUERY(THISFORM.DATAENVIRONMENT.CURSOR1.ALIAS)
        THISFORM.REFRESH

12. User1: Run Form1.

13. User2: Run Form1.

14. User1: Modify the data in Field1, and click the TableUpdate button.

15. User2: Click the Form2 button on Form1, and click the Requery button.

Notice that it does not update with the updated information from User1. Waiting
more than 5 seconds, assuming the REFRESH is set to the default '0,5', then
clicking the Requery button populates the fields with the updated information.

Additional query words: Multi-User Requery Refresh

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Keywords          : kbvfp 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP500a
Version           : 5.0 5.0a
Issue type        : kbbug

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