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

• Microsoft Visual FoxPro for Windows, version 6.0

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.

Additional query words:

Keywords : kbDatabase kbSQL kbVFp600 kbVFp600bug kbVS600sp3fix kbGrpFox kbDSupport kbCodeSnippet
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbbug