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Q131711: HOWTO: Browse a Table While Using Row Buffering in a Form

Article: Q131711
Product(s): Microsoft FoxPro
Version(s): 
Operating System(s): 
Keyword(s): kbnetwork kbvfp300 kbvfp500 kbvfp600
Last Modified: 26-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 3.0, 5.0, 6.0 
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SUMMARY
=======

If a form uses row buffering, a table that is browsed from the Command window
may display uncommitted changes. This article describes factors involved in
browsing buffered data.

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

When buffering is enabled, data is copied to a cursor. All the editing takes
place in the cursor. With row buffering, data is committed when the record
pointer moves, or when a TABLEUPDATE() function is issued. In particular, data
is written to disk when a SKIP command is issued, another work area is selected,
or the table is closed.

The BufferMode property of a form determines the buffering mode if the
BufferModeOverride property of a cursor is set to 1 (Default). If the BufferMode
property is set to 1 or 2, any cursor used by a grid control is enabled for
table buffering. Any other control bound to data uses row buffering. Buffering
can also be set in the BufferModeOverride property of a cursor in the data
environment.

For example, consider a form that contains a text box control bound to a field in
the table. If the BufferMode property is set to 2 (Optimistic), optimistic row
buffering is enabled. If a BROWSE command is issued from the Command window
while the form is running, the following can take place:

- If the form uses a global data session, the BROWSE command and the form use
  the same cursor. Any change made to the cursor is displayed in the Browse
  window.

- If the form uses a private data session, the BROWSE command and the form
  might use different data. The BROWSE command when issued from the Command
  window uses the global data session. Because two sessions are used, the table
  is reopened and the values displayed in the Browse window are the values
  stored in the table on disk. In this case, only committed changes are
  displayed in the Browse window.

Use the CURVAL() function to query the field values from disk. In a multiuser
situation, use the OLDVAL() function to return the original values from disk.

For more information about buffering, search for "Buffering Access to Data" in
the Visual FoxPro Help menu.

Additional query words: lan network multi-user

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Keywords          : kbnetwork kbvfp300 kbvfp500 kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP300 kbVFP500 kbVFP600
Issue type        : kbhowto

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