Q149000: PRB: REQUERY Function Reopens a View’s Table Exclusively

Article: Q149000
Product(s): Microsoft FoxPro
Version(s): WINDOWS:3.0,3.0b
Operating System(s): 
Keyword(s): kbvfp
Last Modified: 10-FEB-2000

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 3.0b 
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SYMPTOMS
========

If you requery a view to refresh it with new data, the table with which the view
is associated will be opened exclusively -- if it has been closed after the view
was opened. This occurs even if SET EXCLUSIVE is off. Requerying a view opens
the associated table if that table is not already open.

WORKAROUND
==========

To make sure that the table that is associated with the view stays open in
shared mode, do not close the table after the view has been opened. For example,
a form may close the table; and then the view gets requeryed.

Another possible resolution to repopulating a control with new data is to set the
rowsource (or recordsource) to an empty string, perform the requery and then set
the rowsource or recordsource to the original value, as follows:

     ThisForm.Combo1.Rowsource=""
     Requery()
     ThisForm.Combo1.Rowsource="<path and name>".

STATUS
======

This problem has been fixed in Visual FoxPro 5.0.

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

If a view is opened and its associated table is not already open, the table will
be opened exclusively or shared depending on current Visual FoxPro settings. For
example, if EXCLUSIVE is set to Off, the table will be opened shared. If the
table is closed while the view is still open, requerying the view with the
REQUERY() function will open the table exclusively no matter what the EXCLUSIVE
setting.

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

1. Make sure EXCLUSIVE is set On by typing the following in the Command window.
  Creating a view requires that EXCLUSIVE be set on.

  " SET EXCLUSIVE ON " (without the quotation marks)

2. Open the \Vfp\Samples\Data\Testdata.dbc database.

3. On the File menu, click New. Then click View, and click the New File button.

4. Select the Customer table from the Add Table or View dialog box.

5. Click the Fields tab, and then click the Add All button. On the File menu,
  click Save, and save the view with the name View_Customer. Close the view.
  Now the view is created.

6. On the Window menu, click View Window. Observe the tables as they are opened
  and closed as you type the following commands in the Command window:

     CLOSE TABLES
     SET EXCLUSIVE OFF
     USE view_customer
     SELECT customer
     WAIT WINDOW IIF(ISEXCLUSIVE("customer"),"Exclusive", "Shared")
     USE
     SELECT view_customer
     =REQUERY()
     SELECT customer
     WAIT WINDOW IIF(ISEXCLUSIVE("customer"),"Exclusive", "Shared")

After you reopen the view, the View_Customer view is open exclusively because
that is the only way a view can be opened. The Customer table will be
automatically opened when the View_Customer view is opened, and because
EXCLUSIVE is set Off, the WAIT WINDOW command shows it as being opened shared.
After you close the Customer table and call the REQUERY() function on the view,
the Customer table is opened exclusively even though EXCLUSIVE is set OFF.

Additional query words:

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Keywords          : kbvfp 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP300b
Version           : WINDOWS:3.0,3.0b
Issue type        : kbprb

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