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Q221624: FIX:Extra EOF Char Inserted with SELECT Within Transaction

Article: Q221624
Product(s): Microsoft FoxPro
Version(s): WINDOWS:5.0,5.0a,6.0
Operating System(s): 
Keyword(s): kbservicepack kbDatabase kbSQL kbvfp500aBUG kbvfp600 kbvfp600bug KbDBFDBC kbVS600sp2 kb
Last Modified: 27-JUL-2001

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The information in this article applies to:

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

You have an application that updates a record in a table, which is buffered, and
the TABLEUPDATE() call is made within a transaction. This application also
executes a SQL SELECT statement against the same table within the transaction.
Another application or program running within a separate instance of Visual
FoxPro then adds a record or records to the same table before the first instance
has committed the changes. When the transaction is written from the first
instance, an extra end of file (EOF) character, ASCII value 26, is written to
the table.

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

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

1. Start an instance of Visual FoxPro. Run the following code from a program
  file:

     CLEAR
     CLOSE DATA ALL
     CREATE DATABASE testdb

     CREATE TABLE testtab1 (F1 C(10) NOT NULL ;
        PRIMARY KEY, ;
        F2 C(10) NOT NULL)
     FOR lnj = 1 TO 10
        INSERT INTO testtab1 (F1) VALUES (PADL(ALLTR(STR(lnj)),10,'0'))
     ENDFOR

     CLOSE DATA ALL

     USE testtab1
     SET MULTILOCKS ON
     =CURSORSETPROP('buffering',5)
     GO BOTTOM
     REPLACE F2 WITH (SYS(2015))
     ?"Before BEGIN TRANS, Estimated - actual length =",TestTable()
     SUSPEND

     BEGIN TRANS
     SELECT * FROM testtab1 INTO CURSOR ctemp NOFILTER
     SELECT testtab1
     =TABLEUPDATE(.T.)
     ?"Within TRANS, Estimated - actual length =",TestTable()
     END TRANS
     =INKEY(1)
     ?"After END TRANS, Estimated - actual length =",TestTable()
     CLOSE DATA ALL
     * Read DBF into a string variable. Could FILETOSTR() in VFP 6.0.
     CREATE CURSOR ctemp (m1 m)
     APPEND BLANK
     APPEND MEMO m1 FROM testtab1.DBF
     lcLast2 = SUBSTR(m1, LEN(m1)-1)  && Return last 2 characters
     USE

     * Report ASCII value of last 2 characters.
     ?"Next to last char ASCII value =",ASC(SUBSTR(lcLast2,1,1))
     ?"Last char ASCII value =",ASC(SUBSTR(lcLast2,2,1))

     PROC TestTable()
        LOCAL lnEstSize, lnActualSize
        SET COMPATIBLE ON
        * lnEstSize = Header size + (record length*record count) + 1
        * The + 1 represents the end of file character, CHR(26)

        lnEstSize = HEADER() +RECSIZE()* RECCOUNT() + 1
        * The actual file size
        lnActualSize = FSIZE(DBF())
        SET COMPATIBLE OFF
        RETURN lnEstSize - lnActualSize
     ENDPROC

2. Start another instance of Visual FoxPro. Set this instance to the same
  default directory as used in the instance of Visual FoxPro opened in step 1.
  Run the following code from a program file:

  USE testtab1
  SELECT testtab1
  APPEND BLANK
  REPLACE f1 WITH (PADL(ALLTR(STR(RECNO())),10,'0'))
  CLOSE DATA ALL

3. ALT+TAB back to the first instance, then from the Program menu choose Resume.
  The estimated file size will be 1 byte less than the actual file size. The
  last 2 characters are both ASCII 26, or the end of file marker. There is one
  extra end of file character, as there should only be a single EOF character.

NOTE: When the table is located on a network drive, the extra character may not
result in the actual table file size differing from the estimated size.

(c) Microsoft Corporation 1999, All Rights Reserved. Contributions by Jim
Saunders, Microsoft Corporation.


Additional query words: KBDSE

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Keywords          : kbservicepack kbDatabase kbSQL kbvfp500aBUG kbvfp600 kbvfp600bug KbDBFDBC kbVS600sp2 kbVS600SP1 kbVS600sp3fix kbGrpDSFox kbSQLProg 
Technology        : kbVFPsearch kbAudDeveloper kbVFP500 kbVFP600 kbVFP500a
Version           : WINDOWS:5.0,5.0a,6.0
Issue type        : kbbug
Solution Type     : kbfix

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