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Q240436: FIX: Repeated SQL SELECT Statements Cause "File is in use" Error

Article: Q240436
Product(s): Microsoft FoxPro
Version(s): WINDOWS:6.0
Operating System(s): 
Keyword(s): kbDatabase kbSQL kbvfp600 kbvfp600bug kbVS600sp3fix kbGrpDSFox kbDSupport kbCodeSnippet
Last Modified: 27-JUL-2001

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The information in this article applies to:

- Microsoft Visual FoxPro for Windows, version 6.0 
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SYMPTOMS
========

You run a program, method, or procedure that repeatedly issues SQL SELECT
statements in a loop. After a very high number of iterations, the following
program error occurs on a SQL SELECT statement:

  Program Error

  File is in use.

CAUSE
=====

Visual FoxPro attempts to use the same temporary file name twice.

STATUS
======

Microsoft has confirmed this to be a bug in the Microsoft products listed at the
beginning of this article.

This bug was corrected in Visual Studio 6.0 Service Pack 3.

For more information about Visual Studio service packs, please see the following
articles in the Microsoft Knowledge Base:

  Q194022 INFO: Visual Studio 6.0 Service Packs, What, Where, Why

  Q194295 HOWTO: Tell That Visual Studio 6.0 Service Packs Are Installed

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

Although the code below uses the SELECT statement to create a cursor, you may
also see this error occur with SELECTs that create files or arrays, because
intermediate temporary files might be created when joins or unions are used.

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

1. Run the following code from a program (.PRG) file:

  LOCAL lni
  SET TALK OFF
  CLOSE ALL
  CREATE TABLE table1(field1 i)
  INDEX ON field1 TAG field1
  INSERT INTO table1 (field1) VALUE (1)
  USE
  FOR lni = 1 TO 1000000
     IF MOD(lni,100) = 0
        @ 2,2 SAY ALLTR(STR(lni))+" Iterations"
     ENDIF
     SELECT field1 FROM table1 ;
        WHERE field1 = 1 INTO CURSOR sqlresult NOFILTER
     USE IN sqlresult
  ENDFOR
  CLOSE DATA ALL

2. The iteration count is echoed to the screen. Let the program run for 839800
  iterations. This may take quite a while, especially on slower computers.

After approximately 839805 iterations, the error described in the SYMPTOMS
section above occurs.
(c) Microsoft Corporation 1999, All Rights Reserved. Contributions by Jim
Saunders, Microsoft Corporation.


Additional query words:

======================================================================
Keywords          : kbDatabase kbSQL kbvfp600 kbvfp600bug kbVS600sp3fix kbGrpDSFox kbDSupport kbCodeSnippet kbSQLProg 
Technology        : kbVFPsearch kbAudDeveloper kbVFP600
Version           : WINDOWS:6.0
Issue type        : kbbug
Solution Type     : kbfix

=============================================================================

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