Q155936: PRB: Closing Table Loses Changes with Table Buffering

Article: Q155936
Product(s): Microsoft FoxPro
Version(s): 5.00
Operating System(s): 
Keyword(s): kbvfp500 kbvfp600
Last Modified: 24-AUG-1999

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, versions 5.0, 6.0 
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SYMPTOMS
========

If you use a CLOSE or USE command to close an open table, and that table uses
Table Buffering and contains uncommitted changes, Visual FoxPro closes the table
and does not save the uncommitted changes. Additionally, no error dialog box
appears when you close the table. This behavior is different from Visual FoxPro
versions 3.0 and 3.0b, which displays an error dialog box if you attempt to
close a table with uncommitted changes.

WORKAROUND
==========

Use the TABLEUPDATE() function to force Visual FoxPro to save the changes before
closing the table.

STATUS
======

This behavior is by design.

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

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

The following example uses the Customer table in the Visual FoxPro
Samples\Data\Testdata database:

1. Run the following code from a program:

     *  Start of code example

     LOCAL nI
     CLOSE DATABASES ALL
     FOR nI = 1 TO 5
        USE HOME() + 'samples\data\customer'
        =CURSORSETPROP('buffering',nI)
        REPLACE company WITH ALLTR(company) + ' ' + ALLTRIM(STR(nI))
        SKIP
        USE          && Closes table
        USE HOME() + 'samples\data\customer'
        BROWSE
     ENDFOR
     REPLACE company WITH SUBSTR(company,1,ATC('1',company,1)-1)

     *  End

  Notice the numeral appended after the company name in the first record, and
  then close the Browse window. Do this for each of the five times the Browse
  window appears. The numbers 1 through 3 appear, but 4 and 5 do not. Number 1
  is no buffering, 2 and 3 are Pessimistic and Optimistic Row buffering, and 4
  and 5 are Pessimistic and Optimistic Table buffering.

2. As a workaround for the above example, modify the above code as follows:

     *  Start of code example

     LOCAL nI
     CLOSE DATABASES ALL
     FOR nI = 1 TO 5
        USE HOME() + 'samples\data\customer'
        =CURSORSETPROP('buffering',nI)
        REPLACE company WITH ALLTRIM(company) + ' ' + ALLTRIM(STR(nI))
        SKIP
        * The following statement is necessary to prevent errors
        * with GETNEXTMODIFIED() if table buffering is not used
        IF CURSORGETPROP('buffering') > 3

          IF GETNEXTMODIFIED(0) > 0    && Checks for any modified records

            =TABLEUPDATE(1)            && Or whatever you want to do
                                       && before you close the table
          ENDIF
        ENDIF
        USE                            && Closes table
        USE HOME() + 'samples\data\customer'
        BROWSE
     ENDFOR
     REPLACE company WITH SUBSTR(company,1,ATC('1',company,1)-1)

     *  End

  The changed record is saved, even when table buffering is used.

REFERENCES
==========

Visual FoxPro 5.0 Help file; search on: "CURSORSETPROP()," "GETNEXTMODIFIED(),"
and "TABLEUPDATE()"

Visual FoxPro 5.0 Readme.hlp file; search on: "Using Visual FoxPro," then
"Closing a Cursor with an Uncommitted Record"

Additional query words: kbdse VFoxWin

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Keywords          : kbvfp500 kbvfp600 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600
Version           : 5.00

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